This is the 2nd most frequent Estonian word.
et
The Estonian word "et" means "that" in English, often used as a conjunction.
Here, 'et' is used as a conjunction, meaning 'that', to introduce a subordinate clause.
Ma arvan, et see on hea mõte.
I think that this is a good idea.
Here, 'et' introduces an infinitive verb clause, which specifies the purpose or goal of the action.
Käes on aeg, et minna koju.
The time has come to go home.
In this sentence, 'et' connects the main clause with the subordinate clause, indicating the content of the statement.