-'s

short form I

1) a way of saying or writing ‘is' and ‘has'. This is not often used in formal writing

She's in the kitchen.

John's gone out.[/ex]

2) the usual way of saying or writing ‘us' when you use it with ‘let' to make a suggestion

Let's not tell him now.[/ex]

II

suffix

-'s

1) used with nouns for showing who or what something belongs to

I've never met Andy's wife.[/ex]

The dog's leg was badly cut.[/ex]

the evening's activities (= activities that happen in the evening)[/ex]

2) used for talking about the home of a particular person

We all went back to Alan's for lunch.[/ex]