There are three types of final -s in some words in English, including plural nouns, verbs in present simple tense for third person singular subjects and as a part of the possessive cases.
Plural Nouns:
In English, we can add -s/-es to the end of a noun in order to make it plural.
book è books school è schools table è tables
box è boxes city è cities dish è dishes
Third Person Singular Subject:
In present simple tense, third person singular subject always takes
-s/-es at the end.
Walt wakes up at 7 every day and goes to school.
Skyler makes breakfast and washes the dishes.
Possessive (‘s):
We add ‘s to singular nouns to show possession.
We are having a party at John‘s house.
Michael drove his friend‘s car.
Note that we add only ( ‘ ) to plural nouns ending in -s:
This is my parents’ house.
Those are ladies’ shoes.