Piacere - to like and Servire - to need

piaccio	piacciamo			servo	serviamo
piaci	piacete			servi	servite
piace	piacciono			serve	servono

Piacere (a) literally means "to be pleasing," so to form a sentence you have to invert the word order. You must also use the prepositional contractions with a.

Maria piace a Giovanni.  John likes Mary. (Literally: Mary is pleasing to John)
Gli studenti piacciono ai professori.  The teachers like the students. (Literally:  The students are pleasing to the teachers).

The most common forms are the third person singular and plural when used with object pronouns. The object pronouns that are used with these two verbs are somewhat similar to the reflexive pronouns:

So to say I like something, use Mi piace if it is singular and Mi piacciono if it is plural.

Mi piace il calcio. I like soccer.
Mi piacciono i treni.  I like trains.

Servire has the same construction as piacere.  It is also used primarily in the third person singular and plural forms and takes an indirect object.

Ti servono della frutta?  Do you need any fruit? (Literally:  By you is needed some fruit?)
Il pane serve a Marco.  Marco needs the bread.  (Literally:  The bread is needed by Marco.)