Reciprocal verbs are used to express the idea of reciprocity - doing something to each other. It usually takes place when the subject needs to be in the plural forms (nosotros, vosotros, and ellos) with the reflexive forms se, nos.

Let's look at some example sentences.

Eugenia y Ana se hablan todos los días.
Eugenia and Ana talk to each other every day.

Los novios se ven todos los días.
The couple see each other every day.

Mis padres se quieren.
My parents love each other.

Todos sus primos se llevaban muy bien cuando eran niños.
All his cousins got along when they were children.

Con mucho gusto, nos vemos la semana entrante.
Gladly, we will see you next week.

In some cases, it takes place when the subject is singular but implies more than two people or things, or when it is a collective noun, for example:

La pareja se quiere mucho.
The couple loves each other very much.