Execution units are components within a computer's central processing unit (CPU) that carry out instructions from programs. Each unit is designed to perform specific tasks, such as arithmetic operations, logic operations, or data manipulation. By having multiple execution units, a CPU can process several instructions simultaneously, improving overall performance. These units work in conjunction with other parts of the CPU, such as the instruction decoder and the register file. The efficient coordination between execution units allows for faster computation and better resource utilization, enabling modern computers to handle complex tasks and run multiple applications at once.