Impersonal constructions with se

-Se- to form a contraction 

- passive voice (you they one)

-sehabla español en Costa Rica 

-Spanish is spoken in Costa Rica 

-se puede leer en la sala de espera. 

-you can read in the waiting room. 

-often used in signs/commercials

-se doesn't change when it's singular or plural 

-se vende ropa, se venden camisas