His logbook shows 340 hours of "time". However, he was paid for the equivalent of 850 hours.. So he made 510 hours of credit without actually flying.
I have a friend that sits reserve at home on wide bodies. Last year, he worked around 23 days. So he probably logged about 100 hours of actual flying time (probably less).
However, he makes a minimum of 75-ish hours a month as a guaranteed minimum, per the contract with his company. So he made around 900 hours of flight pay (credit) last year, while only actually flying 100 hours.
There are a lot of permutations and ways to get "credit hours" but hopefully you get the idea. For example, deadheading: when the company needs to send you somewhere to go fly a plane, you are in the back as a passenger on a company ticket,... but you are paid like you actually flew the jet. Two weeks ago, I deadheaded from SFO to Honolulu. Sat in 1st class, worked on my computer, and slept for almost 3 hours. It was almost a 6 hour flight. When we arrived, I got in the cockpit and flew the jet back. That was about a 5 hour flight. So I logged 5 hours of time... but was paid for 11 hours of time for a single day out-and-back.
The contract between the pilot and the company is a very important legal document. It defines how you will get paid, and for what. And vacation, number of hours per day guaranteed, reserve rules, et...
I know corporate pilots that make bank. Big bank. However, the actual dollars that show up in to your account are only one piece of the puzzle. The contract defines all of those pieces.
In the military, I was proud to be the guy at the top of the 30-60-90 day flying time sheet posted in Ops.
In the airlines, it's the complete opposite.