What does side side side mean in math?

Answer 1

It's a quick way of saying:

"I know that this triangle is congruent to that triangle because each side of this one is

congruent to the corresponding side of that one, and we have learned and proven that

if two triangles have each side of the first one equal respectively to each side of the second

one then the triangles are congruent."

But you're not required to say it the short way. You're definitely allowed to use the whole

un-abbreviated statement if you prefer.