it has a lot of confution in that and what is the perpendicular bisect ?

 Perpendicular bisector is a line segment which divides the other line into two equal halves as well as make an angle of 90° on the other line.

For, in the given figure

PQ is the given line segment and LM be the corresponding perpendicular bisector of given line segment PQ; which cuts the PQ in such a way that

PN = NQ and ∠LNP = ∠LNQ = 90°