Time Codes are useful for teams who have a lot of time entries from different types of resources. The admin section for Time Codes shown in the screenshot below allows you to add new Time Codes and edit them. You can also Import Time Codes straight into the list below.
Project Time Codes will appear as options as you enter time on a task or project level. You can specify that by marking them as No on "Company Entry?" but Yes on the other options.
Non-Project Time Codes will only appear as options as you enter time on the company level, like Administration and Vacation/PTO in the screenshots.
Time Codes on a Task Level