what even are numbers??

i know it sounds like a stupid question but i was just thinking about how i used to think numbers are simply amounts, like 5 apples means an amount, but then i thought about negative numbers and how there isnt any negative amount of anything in the universe,

but like ok so maybe numbers are like "relative" amounts, like if im standing on the roof then someone might have a negative hight compared to me? maybe??

but then i remembered imaginary numbers exist and thouse are definitely NOT amountsof anything, so like what are they?

because when i write the word "chair", its a symbol for a physical thing, so what does the symbol "3" refer to?? what does "7i-2" actualy mean? it cant JUST be meaningless symbols right?