This is the 1073rd most frequent Swedish word.
onsdagskvällen
"Onsdagkvällen" means "the Wednesday evening" in English.
In this sentence, 'onsdagskvällen' specifies the time frame (Wednesday evening) for the action of visiting a friend.
Jag besökte en vän på onsdagskvällen.
I visited a friend on Wednesday evening.
Here, 'onsdagskvällen' indicates a habitual activity that takes place on Wednesday evenings.
På onsdagskvällen brukar jag gå till yogaklassen.
On Wednesday evening, I usually go to yoga class.
In this context, 'onsdagskvällen' defines the time setting for discussing the events of that day.