The "Fetch-Decode-Execute" cycle is a fundamental process used by a computer's CPU to execute instructions. It begins with the CPU fetching an instruction from the memory, which contains the program code. This instruction is then decoded to understand what action is required. After decoding, the CPU executes the instruction, performing the necessary operations, such as arithmetic calculations or data movement. This cycle repeats continuously, allowing the CPU to process multiple instructions in sequence, enabling the computer to run programs effectively.