As the name suggests, this type of grip replaces the original one that was supplied with your racquet.
The surface can be either smooth or patterned which may help to provide a non-slip handle on your racquet.
Some grips have a ridge or a raised central portion that you can grip with your fingers.
Some players prefer a “Tacky” surface that does not slip in their hand, but others prefer a “Dry” surface. This probably depends on how much you perspire during play.
As you can see there are various options, and you will probably have to try several before you find one that you like.