What does the s actually stand for? Well, S basically stands for the Svetberg unit. And this is basically a unit that measures the rate at which the given particle or molecule in this case are a subunit sediments. So the Svetberg unit usually refers to how quickly something sediments or travels along or down a test tube that is basically rotating with some angular velocity. And the Svedberg unit is directly related to the mass of our particle and it also depends on the size and the shape of the molecule. So heavier molecules will be found farther down the test tube than lighter molecules.