Yo toco las flores.
I touch the flowers.
Alguien toca a la puerta.
Someone knocks on the door.
Él toca la guitarra todos los días.
He plays the guitar every day.
Se mira pero no se toca.
You can watch but you can't touch.

Note: tocar is also commonly used in a pronominal/reflexive form with the pronouns me, te, le, nos, os, les, as in the following examples:
to have a turn
Te toca recoger la mesa.
It's your turn to clean the table.
to correspond to
Me toca la mitad.
I get half.