This is the 38th most frequent Swedish word.
blir
"Blir" means "becomes" or "turns into."
'Blir' is used here as a verb meaning 'to become' describing a change in state.
Jag blir alltid glad när solen skiner.
I always get happy when the sun shines.
Here, 'blir' denotes a change in the environment, specifically highlighting the onset of darkness.
Det blir mörkt tidigt på vinterkvällar.
It gets dark early on winter evenings.
'Blir' expresses the consequence of an action that will result in being late.