Reflexives are often used to express a change in: Physical Mental Social condition English= to get, to be getting, to become, to be growing
Reflexives are used idiomatically. Se queja de todo. He complains about everthing. Not He complains himself about everything.
They are used to express a reciprocal action: Vamos a llamarnos. Lets call each other. Se besan. They kiss each other.
A reflexive construction is sometimes used to reinforce the meaning of a verb. El chico come tres pedazos de pizza. The boy is eating 3 pieces of pizza. El chico se come toda la pizza. The boy is eating the whole pizza by himself.