Dihedral is the upward angle of an aircraft's wings, which increases lateral stability in a bank by causing the lower wing to fly at a higher angle of attack than the higher wing. What it really means is that you can fly more hands off, even in turbulence.

How do you improve lateral stability?

A high-wing airplane design, contributes to the lateral stability, whereas a low wing placement has a destabilizing effect in roll. However, this effect may be counteracted by including more dihedral to improve the overall lateral stability. Wing sweep will help promote lateral stability.

What is the purpose of the dihedral angle on a wing?

The purpose of dihedral effect is to contribute to stability in the roll axis. It is an important factor in the stability of the spiral mode which is sometimes called "roll stability".