An oily kind of ingredient that can magically blend with water all by itself. This is called self-emulsifying and SE in its name stands for that.
The difference between "normal" Glyceryl Stearate and this guy is that the SE grade contains a small amount of water-loving soap molecules, such as sodium stearate. This increases Glyceryl Stearate's affinity for water and gives it stronger emulsifying abilities.
Other than that, it’s a nice emollient that gives a smooth and soft appearance to the skin.
You can read some more at Glyceryl Stearate >>