Learn Portuguese (Portugal): Quando é que a aula começa?

é que literally translates to "is it that" (When is it that the class begins?). It doesn't add extra meaning, but it is extremely common in Portuguese to emphasize that you are asking a question. You could just say Quando começa a aula?, but using é que sounds very natural.

Why is there an a before aula?

In English, we often say "class" without "the", but Portuguese usually requires a definite article (o or a) before a noun. Since aula is a feminine word, we use a to say "the class".

How does the word order in this question compare to English?

In English, we use helper words like "does" and change the word order. Portuguese does not do this. If you remove the question words Quando é que, the rest of the sentence keeps the normal statement order: a aula começa (the class begins).

The word começa looks a bit like "commence". Are they related?

Yes! Começa comes from the verb começar, which means "to begin" or "to start". It shares a root with the formal English word "commence", which makes it an easy vocabulary word to remember.