The thing about Plurals
It is hard to remember how to make nouns plural. How do we know when to add to and S, ES, change the Y to I and add es or when the word should stay the same?. It can be hard to know what to do each time but we can use rules to memorize patterns that will help us to improve and reinforce this lesson. Ginger software.com states that "A plural noun is a word that indicates that there is more than one person, animal place, thing, or idea. When you talk about more than one of anything, you're using plural nouns. When you write about more than one of anything, you usually use the same word, simply adding an s, es, or ies to the end".
https://www.englisch-hilfen.de/en/grammar/plural.htm gives a really good breakdown of the rules of pluralization. Myenglishclass1101 recommends this review for mastering plural nouns.