Learn Polish: Mój syn chce studiować, żeby zostać architektem. - My son wants to study to become an architect.

When you use the verb zostać to mean "to become" a profession, the noun that follows must be in the Instrumental case. For the masculine noun architekt, we add the ending -em to make it architektem.

Could I use uczyć się instead of studiować here?

Not really. In Polish, studiować is specifically used for studying at a university or college. If you mean learning in general or studying at a lower school level, you use uczyć się. Since becoming an architect requires a university degree, studiować is the natural choice.

What exactly does żeby mean in this sentence?

Here, żeby translates to "in order to." When you want to say you are doing something in order to achieve a goal, you use żeby followed by a verb in the infinitive (dictionary) form. So, żeby zostać means "in order to become."

Is zostać perfective or imperfective?

Zostać is a perfective verb, meaning it focuses on the completed result of "becoming" something. Its imperfective pair is zostawać, but when talking about achieving a career goal like becoming an architect, Polish speakers almost always use the perfective zostać.