Learn Russian: Наш сын должен стать юристом.

After the verb стать (to become), Russian uses the Instrumental case to describe what someone or something is turning into. Since юрист is a masculine noun ending in a consonant, we add the ending -ом to make it юристом.

What is the difference between стать юристом and быть юристом?

Стать means "to become", which focuses on the transition or the final result. Быть means "to be", focusing on an ongoing state. If the parents said Наш сын должен быть юристом, it would mean "Our son must be a lawyer." Both verbs require the following profession to be in the Instrumental case.

Why is it должен here, rather than должна or должны?

The word должен (must / have to) acts like a short adjective in Russian, which means it changes its ending to match the gender and number of the subject. Because the subject here is сын (a masculine singular noun), we use the masculine form должен. If the subject were a daughter (дочь), it would be должна.

Does должен always mean a strict "must"?

Not necessarily. While it often translates as "must" or "has to", должен can also mean "is supposed to" or "should" depending on the context. Here, it could mean the parents are strictly demanding it, or it could just represent a very strong expectation.