A hypertonic solution has a higher concentration of solutes compared to another solution, typically a cell's internal environment. When a cell is placed in a hypertonic solution, water moves out of the cell to balance the solute concentrations, leading to cell shrinkage or crenation. This concept is important in biology and medicine, as it affects how cells interact with their surroundings. For example, in the case of red blood cells, placing them in a hypertonic solution can cause them to lose water and become dehydrated, impacting their ability to function properly in the body.