A nice song for those who feel they are living through a deep dark night. You are not alone.

When I'm feeling all alone and so far to go
The signs are nowhere on this road guiding me home
When the night is closing in
It's falling on my skin
Oh God will You come close

You light, light, light up the sky
You light up the sky and show me You are with me
I, I, I can't deny
No, I can't deny that You are right here with me
You've opened my eyes so I can see You all around me
You light, light, light up the sky
You light up the sky to show me that You are with me

When stars are hiding in the clouds
I don't feel them shining
When I can't see beyond my doubt
The silver lining
When I've almost reached the end
Like a flood You’re rushing in
Your love is rushing in

You light, light, light up the sky
You light up the sky to show me You are with me
I, I, I can’t deny
No, I can’t deny that You are right here with me
You've opened my eyes so I can see You all around me
You light, light, light up the sky
You light up the sky to show me that You are with me

So I run straight into Your arms
You’re the bright and morning Sun
To show Your love, there’s nothing You won't do

You light, light, light up the sky
You light up the sky to show me You are with me
I, I, I can't deny
No I can't deny that You are right here with me
You've opened my eyes so I can see You all around me
You light, light, light up the sky
You light up the sky to show me that You are with me

Oh oh oh oh oh oh
That You are with me
Oh oh oh oh oh oh
That You are with me
Oh oh oh oh oh oh

ALL ALONE= Completely alone, really alone.

SO FAR TO GO= My destination (home) is still very very far away.

SIGNS= Traffic signs (used in a figurative way). Here it is referring to the signs on the road that tell you which way to go, like when you get to a crossing and you have signs telling you the cities you can find this way and the other way, so you know where to go.

CLOSING IN= If the night is closing in, it is getting very dark.

CLOSE= Near.

LIGHT UP= Illuminate.

DENY= /dɪnaɪ/ Say it's not true.

ALL AROUND ME= Everywhere I can see.

BEYOND= Further than.

THE SILVER LINING= A "lining" is a covering or coating for an inside surface, for example a coat may be made of rough fabric and then, inside, it has a smooth lining so it feels nice when you put it on.
The phrase SILVER LINING is a reference to an English proverb that says "Every cloud has a silver lining". In English weather, clouds are not a nice thing, since you have clouds most of the time and people would prefer to see the sun. A silver lining is a very good thing, since silver, like gold, is a precious metal, very beautiful and expensive. So if you say that every cloud has a silver lining you mean that every bad thing or situation may have a good thing "inside". For example, you lose your job and feel terrible, but maybe that is a good opportunity to find a better job in the future, so that cloud would have a silver lining inside.
What this song says is that sometimes you feel so bad and weak that you just can't think that this cloud you're in may have a silver lining inside, you feel that there is no hope for a better future: "I can't see beyond my doubt the silver lining" (= I can't see the silver lining which is beyond my doubt)

FLOOD= A huge amount of water that flows over dry land and pushes everything away. When it rains very very very much, a river can grow quickly too much and its waters cover all the lands and towns nearby; that is a flood.

RUSHING IN= To rush is to move very quickly. To "rush in" is to come inside (me) very quickly.
The "rush hour" is the time when most people are going to or coming from work, so there are many traffic jams and the streets are full of people rushing by (moving along very quickly).

This song says that no matter how lonely and sad you feel, how many troubles you have, God is always there for you, and if you look for Him, He will light up the sky and bring love into your dark night. With God by your side, nothing will trouble you anymore.

But you can get more specific explanations here, where the author explains how this song talks about his personal experience: The story behind 'Light Up The Sky'.

And this is what he wrote on the band's website:

Hi friends! Light Up The Sky is a song about God's faithfulness. He is with us not only during the good times, but also when we’re walking through life’s valleys. This page is a place where you can share the ways that God has shown you that He is with you so that it can be an encouragement to others. When you post your story, a light will show up on the map. As more and more people share, the map will become brighter and brighter. We all have different stories, but the one thing we all have in common is that no matter what we go through in life, we’re not alone. God loves us and gives us signs to show us that He’s here.

My family and I were involved in a massive car accident earlier this year, on Good Friday. I was driving along a stretch of highway in Colorado with my wife and 3 kids when a car pulled out in front us. He caused us to flip over and we ended up upside-down in a ditch. I remember thinking that I could have just lost my entire family…I saw that my wife was ok and then one by one heard the cries of each of my children. The sound of their voices was as beautiful as when I heard their cries for the first time when they were born. There was an off duty fireman who just happened to be stopped at that intersection. We narrowly missed his car as we flipped over. He and his wife immediately jumped out of their car, opened our doors and helped me get the kids out. They also had blankets to keep our kids warm. We all walked away from that accident without any serious injuries. The trooper who arrived on the scene said it was the worst wreck he’d seen without a fatality. That very well could have been our time, and that would have been ok. God was watching over us and we were very blessed on that day. Good Friday will always be an “even better Friday” for my family and I…and a reminder that God is always with us. – Josh