Doesn't it all come down to: What is the meaning of "is"? Mathematics is all about statements like "a is bigger than b". "3 is prime". Etc. But what is (sic!)

Doesn't it all come down to: What is the meaning of "is"? Mathematics is all about statements like "a is bigger than b". "3 is prime". Etc. But what is (sic!) the meaning of "is"?