This is the 3206th most frequent Polish word.
sie
"Sie" is a reflexive pronoun in Polish, meaning "oneself," used to indicate reflexive actions or in impersonal expressions.
Here, 'się' is a reflexive pronoun, indicating that the subject (she) is performing the action upon herself (learning).
Ona się uczy matematyki.
She is learning mathematics.
In this sentence, 'się' is used as a reflexive particle that makes the verb indicate a state affecting the subject itself.
Dziecko się obudziło.
The child woke up.
'Się' is part of the reflexive verb 'martwić się,' used to construct the imperative mood of not worrying.