Adverbs of time/frequency
Adverbs of time and frequency are those that talk about "when" or "how often" something happens. They modify the verb giving this type of information.
Some common time adverbs are:
Ayer fui al cine con Pedro.
(Yesterday I went to the cinema with Pedro.)
Por la tarde tomamos café y tarta.
(In the afternoon we had coffee and cake.)
El examen será mañana.
(The exam will be tomorrow.)
Some common frequency adverbs are:
Voy a menudo al gimnasio.
(I go to the gym often.)
Ella siempre tiene clase de inglés los lunes.
(She always has her English lesson on Mondays.)
When they are formed by a group of words, not just one, they are called "locuciones adverbiales", e.g. "por la tarde" or "a menudo".