This is the 14277th most frequent Polish word.
protestuj
"Protestuj" means "protest" (as an imperative: "protest" or "object").
Here, 'protestuję' is used as the first-person singular present tense of the verb 'protestować' to express actively opposing something.
Protestuję przeciw niesprawiedliwości.
I protest against injustice.
'Protestujesz' is used as the second-person singular present tense, indicating a question about someone's action of protesting.
Czy protestujesz przeciwko nowemu prawu?
Are you protesting against the new law?
'Protestuj' here is an imperative form, used as a command or request for someone to protest.