It signifies inertia, lack of momentum. It is comparable to brownian motion where partcles in solution move without direction hither and tither and gain no momentum. It is through this property, some of the matter exists in solid form. It also means darkness or delusion when used in context of mental function.
It is just opposite to Tamas. It is vigorous force with resultant momentum.
It is balancing quality of above two opposing forces.
It is characterized by subtlety and luminosity. It is cause of liquid state of cell membrane.