"Bisect" is a mathematical term which means to divide into two equal parts. We can bisect angles, lines, and more. The line that divides is called the "bisector".
sample problem:
If Ray QS bisects angle PQR , m of angle PQS=7x-6 and m
of angle SQR =4x+15,find m of angle PQT.
Since it is mentioned that ray QS bisects the angle PQR, it is understood that the m of angle of PQT is 4x+15. It is because as metioned earlier, to bisect angles or lines, it means dividing into 2 equal parts, thus, bisect equal measurements of angles.