A possessive noun shows ownership. We add an apostrophe -s ( ‘s ) onto a noun to show that the noun owns something.
This is the boy’s bike.
The ‘s on the end of boy shows that the boy owns something. In this sentence, the boy owns a bike.
It’s the boy’s bike.
Mom’s car is in the repair shop.
The ‘s on the end of Mom shows that Mom owns something. In this sentence, Mom owns her car.
It’s Mom’s car.
All single nouns get ‘s at the end to show ownership.
Dad’s golf clubs
Sam’s new puppy
Gina’s red boots
If the noun is a plural noun that ends in –s, just add an apostrophe.
I have two brothers. They sleep in the boys’ room.
Since the boys (plural) sleep in the same room, it’s the boys’ room.
During lunch, all the teachers eat in the teachers’ lounge.
There are many teachers (plural). The lounge is the teachers’ lounge because many teachers gather there.
Use an apostrophe with a noun to show ownership. A single noun gets “s at the end. Mom’s car.
A plural noun ending in -s gets only an apostrophe after the -s. teachers’ lounge