Question

can someone explain me the meaning of the point which I have highlighted!​

Answer 1

i request you to understand with the diagram ..

Answer 2

Magnetic field lines generates from north pole to south pole outside the magnet and inside the magnet it's form south to north pole hence they are close curves(for details have a look at the picture)

The strength of magnetic field is indicated by the degree of closeness of the field lines. Where they are closest together magnetic field is the highest. The field lines are closest at the poles so the magnetic field is strongest at the poles

Hope it did a little bit help to you