This is the 10724th most frequent Swedish word.
kvällar
"Kvällar" means "evenings" in English.
The word "kvällar" is used here to refer generally to multiple evenings as a recurring time when an activity happens.
Jag brukar träna på kvällar.
I usually exercise in the evenings.
Here, "kvällar" is used to specify evenings during a certain condition, namely winter evenings.
Under kalla vinterkvällar sitter vi ofta vid brasan.
During cold winter evenings, we often sit by the fireplace.
In this sentence, "kvällar" refers to specific evenings within the week when an activity takes place.