"Do you speak Spanish" would come in two forms, depending on to whom you are speaking. For a formal tone, one would use "¿Habla usted español?". Informally, it would be "¿Hablas español?"
It depends on two things: 1) who statement is addressed to and the number and 2) the noun gender of the object.
In Spanish, there are different ways of saying 'you':
'tú' is the informal,...
If you are referring to people from Spain, the right word is españoles. But if your are referring to hispanics, the right word is hispanos. People who speak Spanish are gente de habla hispana or...