The verb gustar literally means to be pleasing to but is understood in English as to like. An indirect object pronoun (me, te, le, nos, os, les) always accompanies gustar.

Me gusta el arte.
Art is pleasing to me.

Me         = indirect object
gusta        = verb
el arte      = subject

The two most commonly used subjects with gustar are it (third person singular) and they (third person plural) because what is pleasing is usually an object (singular) or objects (plural). The indirect object pronoun specifies who is pleased.

EXAMPLES:

Me gusta el libro.
The book (it) is pleasing to me.
(I like the book.)

Me gustan los libros.
The books (they) are pleasing to me.
(I like the books.)

Attention:
The verb gustar must agree with the subject (person or thing being liked).

Me gusta el café.
I like coffee.

Me gustan los refrescos.
I like soft drinks.

Attention:
When what is liked is an activity, gustar is followed by the infinitive of the verb. The singular form of gustar is always used in this case.

øTe gusta correr?
Do you like running?