Almost certainly the value of pensions. There are teachers on that list making $65k with "benefits" of 1mm, which is probably the NPV of ~20 years of pension income.
Doesn't seem to add up though, if you keyword search for "teacher" [0], the results are dominated by GCC with consistently elevated benefits. Once you get out of GCC dominated results, the numbers start looking a lot less surprising - until another GCC entry shows up.
My completely uneducated guess is that GCC reports the entire value of the DB pension as "income" for that year, whereas all other institutions correctly report just the increase in value.
Transparent California is also incorrect in a lot of cases. I worked in CA as a seasonal worker and they reported what I would have earned if I worked full time for a year. In reality I only worked at that rate for 3 months making a quarter of what was reported. So I am not sure how much I trust it anymore.