How does osmosis work?
According to this document (https://arxiv.org/pdf/physics/0305011v1.pdf)


  "Water molecules can pass through the membranes in either direction, and they do. But because the concentration of water molecules is greater in the pure water than in the solution, there is a net flow from the pure water into the solution."
  Hydraulic equilibrium is achieved when the lower concentration of water in the high pressure side is balanced by the higher pressure and therefore higher energy pV on that side


This is the diffusion model of osmosis which is easy to understand at your level.