Hello, I hope I could help.
High osmotic pressure means that there is a high concentration of salt in the solution. Low osmotic pressure means otherwise. It moves from the high to low to achieve an EQUILIBRIUM.
In a much simpler sense, consider coffee granules which is about to be dissolved in a hot water. To analogize, lets say the coffee granules are the high osmotic pressure and the water is the low osmotic pressure. If the container that holds the water is made up of glass, you could see that when the coffee is put with the water, the color of the coffee, which is dark brown, diffuses in the water, which is as we all know, colorless. As seconds pass by, the color of the coffee would disperse in the water, creating only one color, which is brown, right. So in effect:
Coffee granules - from dark brown to brown
Water - colorless to brown.
This phenomenon is what you call the equilibrium state in which there is the same concentration of solute in both solutions. As you can see in my example, the color becomes the same right? This means that they had achieved equilibrium. It should not be the other way around. So in a more scientific way, the salts in both solutions have the same concentration at this point of equilibrium.
But, if it is the other way around (from low to high), it requires ENERGY first for it to proceed to happen.