Probably means the emails between her office and Obama’s. She coud hide he emails from her end but could not hide the record of them on other people’s systems when she conversed with them. Obama was emailing her and vice versa... in spite of his claim he only found out about her server in the news like everyone else.
Seems more likely than there being a stash of them in his office right next to emergency blank ballots and the bottle with McCain’s testicles.
Obama installed new WH computers/internet Jan 1, 2017
http://www.freerepublic.com/focus/f-bloggers/3525477/posts
I think it probably means he was spying on lots of people.