The term "tightening up" a story or scene is easy to understand. It is getting from point A to point B with fewer words. It is an editorial comment still aimed in my direction on occasion. If you find yourself in similar straits in your rejection mail, try writing your story as a series of tweets on Twitter. You simply can't do those page-long blocks of description in 140 character squirts (including spaces). I'm having a lot of fun with aTwitMystery, but it is scary. It's writing with the readers looking over your shoulder, and commenting, going into publication with each tweet. I originally did this to bring folks to my website, and it is doing that. However, the twit story genre is the writing equivalent of doing improv.
Nobody knows what happens next, including the author. Will I get Blackbird out of this next tough bind? ---I don't know! You'll find out when I do.