The verbs jugar, tocar and interpretar are often confused. It is no surprise: in many languages they correspond to the same concept: to play (English), spielen (German), играть (Russian)…
The verb tocar is used only with musical instruments. It is used without a preposition:
Juan toca bien ___ el piano = Juan can play the piano well
No sé tocar ___ la guitarra = I can't play the guitar
Saber tocar, like in the last example, means that a person plays quite well.
The verb jugar means to have fun with a game:
Me gusta jugar al fútbol = I like to play football
Mi hijo juega mucho con su hermano = My son plays a lot with his brother
Por la noche juego con el ordenador = At night I play with the computer
If we use the name of the game, jugar is used with the preposition a:
jugar al ajedrez, jugar al dominó, jugar al tenis,… = play chess, play dominoes, play tennis
If we mention the person we play with, or the computer, we use the preposition con:
jugar con mi hermano, jugar con el ordenador
Finally, the verb interpretar means give life to a text or a score: in particular, play the role of a character, recite a poem or play a musical work:
En esta obra Juan interpreta a Hamlet
= In this work Juan plays Hamlet
Ana va a interpretar una suite de Bach
= Ana is going to play a Bach suite