A "processor hour" represents a single computer processor running for 1 full hour.

Example 1: A Maya render runs for 20 hours on 1 processor.
Total render time: 20 processor hours.

Example 2: The same Maya render runs for 1 hour on 20 processors:
Total render time: 20 processor hours

For billing purposes, both jobs would cost the same because they both used the same amout of computer time. The job in Example 2, however, would be completed in one hour, while the job in the first example would take 20 hours.

Additionally, we define a processor as one processor "core". So a dual-core server running for 1 hour would be the equivalent of 2 processor hours.