Final answer:
CPU time represents the actual time the Central Processing Unit spends processing instructions for a process, excluding I/O operations. It is a key performance metric in computing.
Step-by-step explanation:
In the context of the given question, CPU time represents the amount of time the Central Processing Unit (CPU) is actively processing instructions for a process. It does not include the time taken for I/O (Input/Output) operations, which is separate and involves data transfer to or from input/output devices. CPU time is a crucial performance metric in computer systems, as it reflects the actual processing time spent by the CPU on a particular task or process, influencing the overall system efficiency and response time.