This is the 3318th most frequent Polish word.
uczy
"Uczy" means "teaches" in English.
Here, 'uczy' is reflexive, 'uczy się', meaning 'is learning', specifying the act of acquiring knowledge.
Mój brat uczy się angielskiego.
My brother is learning English.
In this example, 'uczy' means 'teaches', indicating teaching as the transitive action of imparting knowledge.
Nauczyciel uczy dzieci matematyki.
The teacher teaches children mathematics.
Again, 'uczy się' is reflexive, signifying the subject is learning, with an emphasis on the speed of the process.