Learn Spanish (Spain): Veo las películas en inglés con subtítulos. - I watch movies in English with subtitles.

In English, we usually say we 'watch' movies or TV, so it is tempting to use mirar (to watch or look at). However, in Spanish, you generally use ver (to see) when talking about watching television, movies, or plays.

Why is there a las before películas when the English translation just says 'movies'?

In Spanish, when you talk about things in a general sense—like movies as a whole category—you must include the definite article (el, la, los, or las). English drops the article for general statements, but Spanish requires it.

Why is it en inglés without an article, if Spanish just required one for las películas?

Even though Spanish often requires articles for general nouns, languages do not take an article immediately after the preposition en. So, it is always en inglés or en español, never en el inglés.