В чем разница she и she's he и he's​

he's : he is or he was

- He's my brother. (He is my brother.)

- He's sick yesterday. (He was sick yesterday).

she's: she is or she was

- She's pretty. (She is pretty.)

- She's absent last week. (She was absent last week.)

we're: we are or we were

- We're here! (We are here!)

- We're scared. (We were scared.)

I'm: I am

I am a student.

you're: you are or you were

- You're are a doctor. (You are a doctor)

- You're a fool. (You were a fool)

they're: they are or they were

-They're cooking for you. (They are cooking for you.)

-They're happy only for seconds. (They were happy only for seconds.)

It is just to shorten the pronoun and the finite verb.