The first frame he's saying the data the presentation is about is worthless because the people who had the information only wanted to be left alone and probably just made some numbers up.
The second frame he's saying that he's not labeled what '14%' is being discussed. So if later on someone says 'You said that this would only take 14% percent of this resource' he can deny it and say that it was 14% of something else the presentation was about.
The third frame we find out that PHB asked for a 'dry run' of the presentation, before the people the presentation is actually for show up, so Dilbert gave him the completely honest version. He's asking the PHB if he wants him to pointlessly run through this meeting (which he's proven will be utterly worthless to everyone involved in the first two frames) one more time, just for the PHB, and not have the energy for all of the blatant lying that's going to happen when the CEO finally arrives.