Question

Please help me with math symbols

Answer 1

it looks like this ~_ this the underscore under the swirl and does that mean?

Answer 2

\(\approx \simeq\)

At some point, these two symbols may be differentiated, but often they are not.

They may mean "approximately equal to" or "similar to" or "asymptotically equal to".

Where are you seeing it. The context may give it away.

Answer 3

Are you talking about congruency, because congruency has two underscores under the swirl while similarity has just the swirl.