Panasonic S5 has a Leica L lens mount and currently there are 52 native lenses available for this mount.
S5 also has a sensor based image stabilization system which means that all of these lenses will be stabilized when used on S5.
Since Panasonic S5 has a Full frame sensor, it has a focal length multiplier of 1x so lenses will provide their original focal length on S5.
You may also also be interested in these:
Panasonic S5 Lenses with Image Stabilization
Panasonic S5 Lenses with Weather Sealings