Line l bisects xy at m and divides xy into two equal parts. name a pair of congruent segments.

The term congruent means exactly equal. Congruent line segments means exactly equal line segments (in length of course).

Since the line L bisects XY at m and divides it into two EQUAL parts, therefore these two parts are said to be congruent.

Based on this, the pair of congruent segments would be XM and MY.