S endings are quite common in English nouns.
You use the –s ending when you want to make a noun plural. This means that there is more than one of the noun.
For example, you can say that you have one cat, but you saw two cats in the pet store.
The addition of the -s at the end tells us that there is more than one cat in the pet store.
With some nouns, the ending you must add to the end of the word to make it plural is different.
Usually, this comes when the ending of the singular noun ends in letters such as x, ch, sh, or f. In these cases, you may have to add -es and possibly change some of the end letters of the word.
For example, you should say one box but two boxes, or one fish and three fishes. You would also say one wolf but six wolves.
