How do ball bearings reduce friction?

Let's consider a wheel rotating

Now, when wheel rotates, the hub (central hole) rubs against the rotating axle

This causes sliding friction

To prevent that, we use ball bearings in the hub of the wheel.

When ball bearings are used, the bearings roll between the hub and axle

Since rolling friction is less than sliding friction. Ball bearings decreases friction

Example

Ball Bearings are used between hubs and axles of Ceiling fans and Bicycles