Learn Italian: Hai sete? - Are you thirsty?

In Italian, physical sensations like being thirsty, hungry, cold, or hot are expressed using the verb avere (to have) plus a noun. So Italians literally say 'You have thirst' (Hai sete) instead of 'You are thirsty.'

Where is the word for 'you' in this sentence?

The pronoun tu (you) is dropped here. In Italian, the verb usually tells you who is doing the action. Since hai only ever means 'you have' (informal singular), adding tu isn't necessary unless you want to emphasize it.

How do I pronounce hai? Is the 'h' silent?

Yes, the 'h' is completely silent in Italian. You pronounce hai exactly like the English word 'eye'. The 'h' is just there in writing so you don't confuse it with the word ai (to the).

How does this become a question without a word like 'do'?

Italian doesn't use helper verbs like 'do' to make questions. You just take the normal statement (Hai sete - You are thirsty) and raise the pitch of your voice at the end to turn it into a question (Hai sete? - Are you thirsty?).