What is "Log on as Batch Job"?

Well, here is the official definition from Technet article Q101366:
"Log on as a Batch Job
SECURITY_BATCH_RID
SeBatchSid
The user can log on to the system as a batch queue facility. This is a group identifier (S-1-5-3)."

But what that REALLYmeans comes from another Technet article (I forgot to save the article number for this one):

"This right is required to run a scheduled task."

Basically, if you run Task Scheduler to run scheduled jobs, the account you use to run the job must have this advanced right. And I believe that Administrators have this right by default.

hope this helps