Learn German: Trinkt dein Vater Kaffee? - Does your father drink coffee?

Vater (father) is a masculine noun (der Vater), and he is the subject of this sentence (he is the one doing the drinking). For masculine subjects in the Nominative case, the word for "your" is just dein. You would use deine if the noun were feminine or plural, like deine Mutter (your mother).

Why does the sentence start with Trinkt?

In German, you form a yes/no question by moving the conjugated verb to the very first position. A normal statement would be Dein Vater trinkt Kaffee (Your father drinks coffee). To ask a question, simply swap the verb and the subject: Trinkt dein Vater Kaffee? Notice that German doesn't use words like "do" or "does" to make questions!

Why does the verb end in -t (trinkt)?

The verb trinken (to drink) needs to match the subject of the sentence, which is dein Vater. Because "your father" is a "he" (third-person singular), we drop the -en from trinken and add a -t. This is the exact same ending you use for er, sie, and es (he, she, it).

Why is there no article like der or ein before Kaffee?