This song has many colloquial and slang forms, so there are many things to explain.

GONNA= (coll.) Going to.

BE ABLE TO= Can.
"Can" is a defective verb (it only has some tenses) and "Be able to" means the same but it's a complete verb (we can use it for all the tenses), so we use the verb "can" in the simple present tense, "could" for the future and conditional forms, and "be able to" for all the other forms.
- I can speak Spanish (present)
- I could dance tango, but I forgot (past)
- I could help you... if I were stronger (conditional)
- I'm able to speak Spanish (present)
- I'll never be able to learn this (future)
- I need to be able to change that (infinitive)

MAKE IT= Come here, go there, arrive.
- Sorry, I can't make it= sorry, I won't be able to meet you.
- We took a taxi to be faster, but we couldn't make it= we didn't arrive there in time.
- It's too late, you can't make it to the trains= You won't arrive to the railway station in time.
- Your birthday party? Sorry, I can't make it, I'll be away for a week= I can't go.

I GOT IT= (coll.) I have it, I've got it.  (also, in other contexts: I understand).

ACTUALLY= In fact.

'K= Ok.

'CAUSE= (coll.) Because.

THE LAST THING I NEED...= I definitely don't need that.

THINK YOU GOTTA...= (coll.) Do you think you have to...
In colloquial speech it is not uncommon to drop the subject pronoun if it is obvious, and also drop the auxiliary DO for questions.

KEEP ME ICED= (coll.) Buy me a lot of diamonds/jewels (diamonds look like ice).

THINK I'M GONNA= (coll.) Do you think I'm going to...?

CASH= (coll.) Money in general.
In standard English, "cash" is the real money you can touch (coins and bank notes/bills), as opposed to cheques, credit cards and other forms of virtual money. But in colloquial English we use "cash" simply as a synonym for "money".

BROKE= With no money.

LOVE DON'T COST A THING= Love costs absolutely nothing.
In very colloquial English they can use "don't" for the third person singular instead of "doesn't".
This expression follows the same rules as other emphatic negatives:
- She didn't say a word= She was completely silent
- He couldn't walk a step= He couldn't walk anymore
Etc
- I don't hear a sound= I can't hear everything; everything's silent.

WANNA= (coll.) Want to.

BENZ= Mercedes-Benz (an expensive German car brand)

FLOSS= To floss is to clean the space between your teeth using a floss, a special waxed thread (see to floss)

I GOT MY OWN= I have my own floss, I'm not going to use yours, don't worry.

ROLL UP= (slang) Arrive.

ESCALADE= (slang) Large car, luxurious car.

DUB= (slang) 20 dollars (a 20-dollar bank note)

VALET= /væleɪ/ (also /vælɪt /) An employee, as in a hotel or on a ship, who performs personal services for guests or passengers (in this case, he got his car to park it, so the man gave him a huge tip because he was very rich).

KNEW THAT IT WAS GAME= (coll.) I knew that something was going to happen, that you liked me.

SLEEVE= The part of a sweater, jacket, etc. that covers your arms.

ROLLEY= A Rolex watch (a very very expensive brand of watches)

BLING= (coll.) Shine (talking of jewellery, especially when they're flashy and ostentatious.
(Rolex are often made of gold, so that's what she probably means here)

BOOTH= (slang) A very cool place (in this case, an expensive stylish bar)

A TOAST= The action of raising your glass of wine (or another drink) and say you drink to honour somebody or something, or you simply say "cheers" (often touching other people's glasses with yours to make them go "cling").
When toast is uncountable, it means slices of baked bread, usually for breakfast:
- For breakfast I have milk and toast, usually two pieces of toast.

AMISS= Faulty, not working properly.

THINK YOU OUTTA KNOW= I think you should know (OUTTA /ɔ:tə/ or /ɔ:Rə/ = Ought to = should)

BALLIN'= (slang) Partying, having a wild time.

ALL THAT MATTERS IS...= The only important thing is...

TRYNA'= (coll. spelling) Trying to.
(trying to = tryin' to --> in American English N+T often = N)

WAY TOO MUCH= "way too" is an emphatic form of "too".

HIT THE ROAD= (coll.) Leave.
In colloquial English, to hit a place is to go there:
- Hit the road Jack, and don't you come back no more = Go away and never come back (go to the road = take your car and go to the road = go away, very far away)
- After exercising, we all hit the showers (we went to the showers)

WHERE'S MY KEYS= The word "keys" is plural, so it should be "where are my keys". But on Jennifer's mind, "the keys" is just one single object, so she's thinking about it in the singular (the keys, attached to a keyring, makes up one single object, even with different parts).