The phrase "loose leash" means that the leash connecting a dog to its owner is not tight or tense. It allows the dog to walk comfortably without pulling or tugging on the leash. Full definition
We will be working on loose leash walking with distractions, meet and greet with people and dogs, settle in public, and general manners. (2speakdog.com)
You will also practice turns and movement with loose leash walking as well as place, take it / leave it and the drop command. (edmontonhumanesociety.com)