Which one does it mean?
I'll be at work later today.

1. I'll go to work later. (I''m not at work righ now)
2. I'll work a few hours. (I''m at work righ now)

Question

Which one does it mean?
I'll be at work later today.

1. I'll go to work later. (I''m not at work righ now)
  2. I'll work a few hours.   (I''m at work righ now)

Answer

The original sentence, "I'll be at work later today," could mean either: I'm not a work right now, but I'll be there later day, OR (I am at work now), but I'm leaving for awhile, and I'll be (back) at work later today. (In the second instance, a lot of people would definitely include the word "back". But some wouldn't!) So you can't necessarily conclude, without context, that the speaker is not at work when he says, "I'll be at work later today."

Answer

Hello,the first one.
It means : 
I´ll be at my work place later today.