What is equavalit set?

Answer 1

I assume the question is meant to be about equivalent sets.

Two sets are said to be equivalent if they have the same cardinality. For finite sets, it means that they must both have the same number of distinct elements. More generally, two sets are equivalent if (and only if) there exists a one-to-one mapping (bijection) from one set to the other. This definition applies to equivalence of infinite sets but does give rise to some counter-intuitive results. For example, the set of all integers is equivalent to its proper subset, the set of all odd integers. The mapping for all to evens is x-> 2x.