This is the 17126th most frequent Polish word.
włączyli
"Turned on" or "activated."
Here, 'włączyli' is used in the context of activating or turning on an electrical device (the lights).
Wczoraj włączyli światło w pokoju.
Yesterday, they turned on the light in the room.
In this sentence, 'włączyli' signifies joining or taking part in an activity (the discussion).
Na lekcji włączyli się w dyskusję.
During the lesson, they engaged in the discussion.
Here, 'włączyli' is employed to mean triggering or setting off a notification system (the alarm).