The lower surface is partially covered. The wing tips are rotated or curved forward . The dihiedral helps the cockpit and pilot settle easily below the wing. This is very helpful when being knocked about by thermals or gusty air. The pilot does not have to work hard to keep the plane flying upright.
Turns coordinate themselves with natural beauty when a proper dihedral is present.
Again, less work for the pilot. When the wing tips are flying but the wing center is stalled, the center of lift is moved back. This lets the nose drop with the stall instead of a dangerous tail drop. Since the wing doesn't stall all at once, there are not ,likely to be big surprise stalls. It is said that a Weedhopper wing will not spin unless its factory design has been modified.