uczy

In a sentence

• Mój brat uczy się angielskiego.

  My brother is learning English.

  Here, 'uczy' is reflexive, 'uczy się', meaning 'is learning', specifying the act of acquiring knowledge.

• Nauczyciel uczy dzieci matematyki.

  The teacher teaches children mathematics.

  In this example, 'uczy' means 'teaches', indicating teaching as the transitive action of imparting knowledge.

• Ona uczy się szybko.

  She learns quickly.

  Again, 'uczy się' is reflexive, signifying the subject is learning, with an emphasis on the speed of the process.