This is the 383rd most frequent Czech word.
proto
"Proto" in Czech means "therefore" or "that's why."
Here, "proto" means "therefore" as it introduces the consequence of the prior clause.
Nepřipravil jsem se na test, a proto jsem neuspěl.
I did not prepare for the test, and therefore I failed.
In this sentence, "proto" also means "therefore," showing the reason behind the action.
Mám rád sport, proto chodím často běhat.
I like sports, therefore I go running often.
Here, "proto aby" is used to indicate purpose, translating to "in order to."