A hypertonic solution has more osmolarity than the cell. This causes the water inside the cell to go out since the osmolarities tend to equalize. And the cell does not allow the passage of other substances except water. Therefore the water will come out and the cell will shrink.
In a hypotonic solution, the water will enter into the cell and in an isotonic solution the water will be moving into and out of the cell at the same rate.
