But when non-Euclidean geometry forced the nineteenth century mathematicians to discard empirical consistency in favor of logical deducibility, mathematics had a problem. Assuming axioms or first principles and deducing theorems, and then claiming that the truth of the theorems follows from the truth of the axioms, in no way deals with the truth of the axioms. The classic approach is to assume it. You can see that this quickly becomes a philosophical quagmire. It leaves truth to the philosophers.
Fools rush in where angels fear to tread.
But, can mathematics totally avoid any mention of truth. We can deal with that. But, again, it never turns out to be that simple. What he did was prove that there exist statements which are neither provable nor disprovable. How he did this is rather interesting.