What is the meaning of the locus of points P satisfying some conditions?

Question

A rod AB of length 15 cm rests in between two coordinate axes in such a way that the end point A lies on x axis and end point B lies on y axis. A point P(x,y) is taken on the rod in such a way that AP = 6 cm. Show that the locus of P is an ellipse.

I understand the definitions of the rod and of P. But I can't make heads or tails of the last statement. What is meant by the locus of P?

Answer 1

The locus of P is the set of points which P covers/forms, when A and B are being moved/varied while still satisfying the conditions from the problem statement.

Answer 2

As A and B move along the x and y axes, respectively, P moves over the xy-plane.