The phrase "to reinforce the lesson" means to strengthen or remind someone about what they have learned in order to help them understand and remember it better. Full definition
Role - playing exercises are a great way to reinforce lessons on having a good service attitude and interacting with customers. (petbusiness.com)
Generally, teachers introduce new material to students while teacher assistants help reinforce the lessons by working with individual students or small groups of students. (bls.gov)
The dining facility serves as a learning center, offers fresh food prepared onsite, and reinforces lessons learned in the classroom. (ecoliteracy.org)