Question: I was studing how to say school subjects in mandarin and I saw this sentence:

我最喜欢的科目**有**艺术，中文和化学
(My favorite school subjects are art, chinese and chemistry)

Why the use of 有 in this sentecence?

Could I say/write: 我最喜欢的科目是**是**艺术，中文和体育

Answer: 
I have some issues with the first sentence, though it is not wrong. I would say:

我最喜欢的科目有三個 - 艺术，中文和化学 (There are three of my most favored school subjects - ... or

我最喜欢的科目包括 艺术，中文和化学 (My most favored school subjects include ....

The second sentence is perfectly correct.
Both should be fine, it might be easier to think about those ones as some sort of a colon symbol(its basically what it does in this context).

a colon symbol referencing this site <https://grammar.yourdictionary.com/punctuation/grammar-colon-usage.html>

"Use a colon to introduce an item or list, if the list comes after a complete sentence or independent clause..."