I'm very frustrated with this verb offrire. Sometimes it means offer, sometimes buy, sometimes serve… I don't know how to translate it correctly!
Indeed, it makes sense in Italian but not in English because there's no context. In English, one might say, "What can/shall we offer them." In Italian, it's a common phrase within the context of hospitality.
What do we offer? doesn't sound like idiomatic English. Would this be translated: "What can we offer you?" as in: "What can I get you?"
It seems to me that this is an expression rather than a literal translation. When someone is at our house, we say what can we get you? What can we offer you? (This is true both in English and in Italian). It is implied and seems to be understood that we are offering a house guest something to eat or drink.