Not understanding, i’ll give BRAINLIEST!

Answer:
The two angles are alternate interior angles.
Step-by-step explanation:
When two parallel lines are cut by another line, their alternate interior angles are congruent. I like this explaination by varsity tutors:
"The Alternate Interior Angles Theorem states that, when two parallel lines are cut by a transversal, the resulting alternate interior angles are congruent."