Learn Italian: Usi la carta di credito al supermercato? - Do you use the credit card at the supermarket?

In Italian, you don't use helping verbs like "do" or "does" to ask a question. Usi simply means "you use", and your tone of voice or a question mark turns it into a question. The pronoun tu (you) is also dropped because the -i ending on the verb already tells us exactly who is doing the action.

Why does it say carta di credito instead of putting "credito" first?

In Italian, you generally can't put a descriptive noun in front of another noun like you do in English (credit card). Instead, the main object comes first, followed by di (of) and then the description. So, it literally translates as "card of credit".

Where does the word al come from in al supermercato?

al is a combined word (called an articulated preposition). It merges the preposition a (at/to) with il (the masculine singular word for "the"). Since supermercato is a masculine noun, we need il, and a + il naturally glue together to form al.

Could al supermercato also mean "to the supermarket"?

Yes, the preposition a can mean both "at" and "to". You have to rely on the context. Here, you are doing an action inside a location, so "at the supermarket" makes the most sense. If the verb was about traveling, like vai (you go), then al supermercato would mean "to the supermarket".