What Does Clock Speed Mean?
Clock speed is the number of cycles per second produced by a crystal oscillator, which regulates the timing for a synchronous circuit, such as a CPU. Clock speed is measured in megahertz (MHz) or gigahertz (GHz).
Techopedia Explains Clock Speed
A faster clock speed can speed up processing, but increasing the clock speed at an accelerated rate can sometimes be harmful to a PC, especially if other components are not upgraded. Depending on the CPU, it can process one or more instructions per clock pulse. Newer PCs can process more than one instruction per clock pulse and usually have a larger bus, which determines how fast data on the motherboard is moving.