No, it's the proof that the set of reals is larger than the set of natural numbers, even though the set of odds numbers is exactly the same size as the set of naturals. The proof is that you could match odds and naturals 1 to 1 forever. Match 1 with 1, 2 with 3, 3 with 5, 4 with 7, etc. You're not gonna run out of odds. But if you try to match naturals with reals, you run out. 1 with 1.01. 2 with 1.001, 3 with 1.0001. Etc. You will run out of naturals before you get anywhere.