kvällar

In a sentence

• Jag brukar träna på kvällar.

  I usually exercise in the evenings.

  The word "kvällar" is used here to refer generally to multiple evenings as a recurring time when an activity happens.

• Under kalla vinterkvällar sitter vi ofta vid brasan.

  During cold winter evenings, we often sit by the fireplace.

  Here, "kvällar" is used to specify evenings during a certain condition, namely winter evenings.

• Många kvällar i veckan tillbringar hon med sina vänner.

  Many evenings of the week, she spends with her friends.

  In this sentence, "kvällar" refers to specific evenings within the week when an activity takes place.