It is confusing to be a dog. One way we can make dogs lives easier is by marking their behavior. Similar to a game of hot and cold, marking behaviors helps dogs realize if they did the right move or the wrong move. I like to use the word yes when my dog does the right thing. Marking the right thing is what we are doing when we do clicker training. Some dogs respond better to the sound of the click then to a word yes. However, for me I have a hard time remembering the clicker so I generally go with the word instead of the clicker. You can do whatever works best for you and your dog. The concept is simple. You make the dog associate all things positive with the yes or the click. Then once the dog understands that good things come from the positive marker, you can start using it in practice. As soon as the dog does the behavior your looking for you let them know good job with the marker.
Why is this important? Besides helping dogs understand the puzzling world of humans, it also helps prevent bribery and gives you time to reward. You are not holding treats or toys under the dogs nose or begging them with the toy or treat to be good. The treats are generally kept away. The dog gets the marker when they do right. The timing with marking is critical so that the dog can figure out the "right" behavior. The reward can follow or when the dog is ready you can move into intermittent rewarding.
There are trainers that chose to only let the dog know if they have made the right move. However, for me, I want my dogs to know if they are on the right or wrong track. I want them to know to keep trying for a different answer. I think the more information I can provide my dog to help figure out if they are right or wrong helps the dog figure out the right answer. I make a nope type noise for no. Usually when my dogs hear that noise they stop what they are doing and try offering me a different behavior trying to get it right.