Appreciate it, I'll try those.>个
Ah yeah, that's a huge thing.
There's a billion of these "measure words", 个 (ge) is the generic one, so if you're not sure which measure word to use, use 个.
I've seen other explanations but the one that make sense to me is this:
In English, we have words like "paper" where you can't usually say "3 papers", you have to measure it somehow and say "3 pieces of paper". Chinese has no plural words so you have to do this for literally everything. You would say something like "3 fruits of apple" instead of "3 apples". The word you add is called a measure word, so you'd say "3 个 apple".
Same for if there's not a specific number. "how many apples" becomes "how many 个 apples".
What gets confusing is that you sometimes need to do this if there's only one. If you say "I want an apple", you don't need a 个, you can just say "I want apple". But if you say "that apple" you do need to say "that 个 apple". Lots of times, you technically can use a measure word "I am 1 个 doctor", but it's obvious you're not two doctors so you just say "I am doctor".
If I ever come up with a really simple explanation for when you do or do not use measure words, I'll let you know, but as far as I know it's not very simple. But definitely use them with plurals, and reference words like that/this/which/etc.
There are a billion measure words depending on what you're talking about, flat things like maps and tables use 张, 位 is a polite measure word for people, etc. I don't know many because I honestly don't know many nouns.