This is the 89th most frequent Finnish word.
jotta
"Jotta" means "so that" or "in order to" in English.
In this sentence, "jotta" introduces a purpose or goal clause, explaining the reason behind the main action, that is, studying.
Hän opiskelee paljon, jotta hän voisi menestyä kokeessa.
He studies a lot so that he can succeed in the exam.
Here, "jotta" is used to indicate the desired outcome or intention of the action of closing the window.
Suljen ikkunan, jotta säästämme energiaa.
I close the window so that we save energy.
In this context, "jotta" shows the aim of the main clause's action, being quiet.