Answer
Probably, the acid and the base from which the salt is derived have the same strength. Or they both are a strong acid/base pair, or the acid's $K_a$ is equal to the base's $K_b$.
Work Step by Step
There are to possible explanations if the resultant solution from a certain salt is neutral:
1. Both ions do not hydrolyze, which means that the acid and the base from which the salt is derived are both strong.
2. The cation and the anion are, respectively, a acid and a base with equal strength, and they ended up neutralizing each other. This means that the acid and the base from which the salt is derived have the same strength.
But, that is not very common to happen, so, probably, the acid and the base are strong as indicated by the first option.