Learn how to ask age: How old are you? And remember:
To tell the age we use the verb "to be" and we have two options:
1- I am 24
2- I am 24 years old
(but it's not correct to say: I am 24 years).

There is some vocabulary about age too.

TELLING AGE

How old are you?
I'm twenty-two years old. How old are you?
I'm forty years old.
How old is your wife?
She's in her mid-thirties.
I have a sister who is in her mid-thirties.
How old are your parents?
My dad is 56 and my mum is 54. How old are your parents?
They're both old. My father is 82 and my mother is 78.
Wow. Are they healthy?
They can still move, just slower.
Haha. My little brother is a teenager.
How old is he?
He is 15.
Do you have any other siblings?
Yes. I have a baby sister. She's a toddler.
How old is she?
She's two years old.
Cute!
She is a cute toddler.
My sister has a newborn.
How old is the newborn.
He's three weeks old.
Wow. Tell her congratulations.
Thank you. I will.

HOW OLD ARE YOU?= What's your age?

SHE'S IN HER MID-THIRTIES= She is 33-37 years old.

A TEENAGER= A boy or girl who is 13-19 years old. An adolescent.

SIBLINGS= (formal) Brothers or sisters.

A BABY SISTER= A sister who is 1-4 years old (or maybe 1-6)

A TODDLER= A baby who is still learning to walk correctly (about 1.5-3 years old)

CUTE= (coll.) Nice, beautiful and lovable.

A NEWBORN= A baby born recently.