Talking about food and eating out
Vous voulez manger quoi ?
Je préfère le filet de boeuf
To find out what someone would like to eat, use the question
Qu'est-ce que vous voulez manger ?
or more chattily,
vous voulez manger quoi ?
Voulez is from the verb vouloir (to want) and the form for "I want" is je veux. But, just as in English, it's more polite to say je voudrais (I would like).
To ask what someone else prefers and say what you prefer, use the verb préférer. It's regular, apart from a change of accents, which alters the pronunciation, of course.
There are several conversational expressions to show that you agree with a suggestion:
I'm hungry is j'ai faim. J'ai is from the verb avoir (to have), so what you are saying literally in French is 'I have hunger'. It's one of a number of common expressions using avoir in this way: j'ai soif (I'm thirsty) j'ai froid/chaud ( I'm hot/ cold)