10339 is the process number for one of your apps. I've seen this happen after I uninstalled an app, and then checked battery life later that same day.
GSam Battery Monitor shows the process number as App UID. When I saw the number in Settings\Battery, I wasn't exactly sure what to make of it; so I then went into GSam and saw a number instead of an app name in App Usage.
I had uninstalled an app earlier that day, and the above GSam process helped me to remember, and thus be able to correlate that the number represented the app that I had previously uninstalled.