Segment RQ is congruent to segment KL. The reason is because with ASA you need to have a side in between two angles, and in this case those are the only two sides that would both be in between the two angles
ASA is short for Angle-Side-Angle. To use this congruence postulate, you need to have two angles and the side between them shown to be congruent. In the left triangle, the two angles are R and Q, so the side between them is RQ. In the right triangle, the corresponding angles are K and L, so the side between them is KL. That is, you must have ...
RQ ≅ KL
in order to use ASA to show the triangles congruent.
____
It is all about matching patterns. We have explained this pattern-matching process several times now.