Learn French: Est-ce que tu aimes les vacances ?

Est-ce que literally means "is it that". Placing it at the beginning of a statement is the most common way to turn it into a yes or no question in French. Here, it changes the statement tu aimes les vacances (you like vacations) into a question.

Why is it les vacances (plural) when English speakers often just say "vacation"?

In French, the word for a holiday or time off from work or school is always plural: les vacances. If you use the singular form (la vacance), it means a "vacancy" like an empty hotel room or a job opening, not a holiday!

Why do we need the word les here? Can I just ask if you like vacances?

No, you cannot skip it in French! In English, we drop the word "the" when talking about things we like or dislike in general (such as "I love pizza" or "Do you like vacations?"). In French, you must always use a definite article (le, la, l', or les) when expressing preferences.

Since tu ends with a vowel and aimes starts with one, why isn't it written as t'aimes?

Unlike the word je (which shortens to j' before a vowel), the word tu never drops its final vowel in written French. You will often hear native speakers say t'aimes in casual, fast speech, but it must always be written as tu aimes.