This is the 907th most frequent Czech word.
protože
"Because."
Here 'protože' introduces the reason for the action described in the main clause.
Protože prší, zůstaneme doma.
Since it's raining, we will stay home.
In this sentence, 'protože' specifies the necessity causing the speaker to not go out.
Nemůžu jít ven, protože musím pracovat.
I cannot go out because I have to work.
In this context, 'protože' links the emotional state to its cause.