This is the 2558th most frequent Portuguese word.
estuda
"Estuda" means "studies" (third-person singular or second-person singular in formal speech).
In this sentence, 'estuda' is the singular third-person present indicative form of 'estudar' (to study), used to express the regular action of studying.
Ela estuda matemática todos os dias.
She studies mathematics every day.
Here, 'estuda' serves as the singular second-person present indicative form of 'estudar' and is used to pose a question, encouraging someone to study.
Por que você não estuda antes da prova?
Why don't you study before the exam?
In this instance, 'estuda' is used as the singular third-person present indicative form of 'estudar' to denote a habitual action performed by the brother.