There are two ways to address people in español:

Tú form: familiar, informal, for close acquaintances.

Tú comes la zanahoria.
     You eat the carrot.
Tú juegas con la silla.
     You play with the chair.
    Tú estás contento.
     You are happy.
    Tú tienes gripe.
     You have a cold.

usted form: formal, for older or higher rank people (more respectful).

    Usted come la zanahoria.
     You eat the carrot.
    Usted juega con la silla.
     You play with the chair.
Usted está contento.
     You are happy.
Usted tiene gripe.
     You have a cold.