Seiya
Wa
Eiga
Wo
Miru
In English, you add "s" to a noun to make it plural but we don't do this because pluralization doesn't exist in Japanese.
This sentence can be translated as:
Seiya watches a movie
Seiya watches movies
We don't really care about how many movies Seiya watches unless the number is an important subject of the conversation.
More info
Even though we don’t differentiate singulars and plurals in Japanese, we have a special suffix that we can add to certain nouns to clarify that the noun is plural.