The noun simplification can be countable or uncountable. In more general, commonly used, contexts, the plural form will also be simplification. However, in more specific contexts, the plural form can also be simplifications e.g. in reference to various types of simplifications or a collection of simplifications.

What is the plural of simplify?

/ˌsɪmpləfəˈkeɪʃən/ noun, plural simplifications [count, noncount]

What is simplification in English grammar?

British English: simplification NOUN /ˌsɪmplɪfɪˈkeɪʃən/ act Simplification is the act or process of making something simpler. Everyone favours the simplification of court procedures.