According to the doc the time unit is "jiffies" As in, "I'll be there in a jiffy!" :)
A jiffy is equal to the time it takes light to travel one centimeter in a vacuum or approximately 33.3564 picoseconds. - Wikipedia
But that's not the definition you want. Try this post https://stackoverflow.com/questions/10885685/jiffies-how-to-calculate-seconds-elapsed where the top answer says
The size of a jiffy is determined by the value of the kernel constant HZ.
The value of HZ varies across kernel versions and hardware platforms. On i386 the situation is as follows: on kernels up to and
including 2.4.x, HZ was 100, giving a jiffy value of 0.01 seconds;
starting with 2.6.0, HZ was raised to 1000, giving a jiffy of 0.001
seconds. Since kernel 2.6.13, the HZ value is a kernel configuration
parameter and can be 100, 250 (the default) or 1000, yielding a
jiffies value of, respectively, 0.01, 0.004, or 0.001 seconds. Since
kernel 2.6.20, a further frequency is available: 300, a number that
divides evenly for the common video frame rates (PAL, 25 HZ; NTSC, 30
Conclusion: divide a schedstat time value by the system's HZ constant to convert to seconds.
Update: If you're dealing with these times in a programmatic context, the now top answer on that same page points to some system routines that you can call to do conversions (e.g. jiffies to milliseconds).