Informal: ¿Te gusta el español?
Formal: "¿Le gusta el español?
But, as people from Spain are also "español" to be clear with the question you can say:
Informal: "¿Te gusta el idioma...
The word can in Spanish comes from the verb "Poder" (which literally means 'to be able to'). It is conjugated differently depending on who/what you are talking about. I can = Puedo You can = Puedes...