What does the equal sign with the wavy line above it mean?

Answer
This sign means “congruent to”.

Explanation
The equal sign with a wavy is ≅. It means equivalence of geometric shapes and size.
For example, triangle ABC ≅ triangle XYZ. This means that triangle ABC is congruent to triangle XYZ.  

Many things that seem threatening in the dark become welcoming when we shine light on them