The phrase "to learn this lesson" means to understand and remember something important that you experienced.
Sentences with «to learn this lesson»
If we do not learn any lessons from the past about the creation of environmental justice communities... we're going to create new ones. (scientificamerican.com)
Some though, haven't learned the lessons of the past. (firstthings.com)
Of course, a fan asked her how she hadn't learned her lesson from all those years before. (video-games-galore.com)