Answer:
Through concentration gradients and a semi-permeable membrane.
Step-by-step explanation:
Imagine a semi-permeable membrane splitting a beaker into two sides which only water can pass through and salt cannot.
One side is filled with much more salty water than the other. (the saltiness, not the amount of water).
Since the salt cannot pass through the membrane, one side's salt is much more concentrated than the other.
In an effort to restore equilibrium, more water passes to the saltier side to balance out the ratio of water : salt.
Since one side has more salt, more water is needed to balance that out, and hence water moves towards the saltier side.
Hope this helped!