"A school is a place."
It can work but i guess its not appropriate in this type of sentence just like engliah grammer
I think it you could perhaps say that if you had a specific school in mind(?), but generally it would be more natural to use the topic marker than the subject marker for general "X is Y" statements.
은/는 (subject participle) We use it to continue speaking about the current subject of discussion
I wrote 학교가 instead of 학교는 and didn't work. I kind of get why it didn't work, and I'm ok with the correction of writing it as 학교는 and not 학교가, but then they asked me to translate "학교가 장소입니다" from Korean to English. Is this a bug? Maybe I wrote right the first time, I don't know...
은/는 marks the subject of the sentence. Which one you use depends on the verb's ending letter.