This is the 116th most frequent Swedish word.
eftersom
"Eftersom" means "because" or "since" in English.
Here, 'eftersom' connects the event of interrupting the meeting to its cause, the inability to reach an agreement.
De avbröt mötet eftersom ingen kunde komma överens.
They interrupted the meeting because no one could agree.
This usage of 'eftersom' links the reason for Lisa's happiness to the event of her passing the test.
Lisa är glad eftersom hon klarade provet.
Lisa is happy because she passed the test.
The word 'eftersom' is used to introduce a reason, explaining why the action in the main clause is happening: staying at home due to not feeling well.