Question

in light lesson Plus sign and a minus sign what indicates

Answer 1

when there is -ve sign The light comes from that area.
and the area in which light goes it will be represented by +ve sign

Answer 2

In the chapter
The distance measured in the direction of light is taken as positive.
those measured in opposite direction is taken as negative.
Height of object and height of the image are positive if measured upwards of axis and negative if measured downwards.
for concave magnification is negative.
convex magnification is positive.