Hola Patricia

I imagine you are referring to this testquestion:

Nosotras vamos a salir de copas el viernes próximo. (We are going to have drinks next Friday.)

We are using salir because we can't translate literally as it wouldn't make sense in Spanish. In English you say to have drinks, but in Spanish we don't say "tener copas". It's very common to say "salir de copas" meaning "to go out drinking", "to go out and have some drinks". 

You can use the verb tomar though for "having a drink", so this could have also been correct by saying "Nosotras vamos a tomar unas copas el viernes próximo".

I hope this clarified it.

Saludos

Inma