Lucid dreaming is being aware you are dreaming while in a dream. After that point, you are able to take control of your dream, being able to do things like fly, breathe underwater, meet a fictional character, practice skills, come up with new ideas, heal from trauma, and far more.
There are multiple ways to induce a lucid dream, but a key part of having a proper lucid dreaming practice is to improve your dream recall by writing down the details of your dreams right after waking up each morning. It is also important to perform multiple reality checks each day since you will be likely to perform one in your dream and then realize you are dreaming.