The phrase "to roll on" means to continue moving forward or progressing without any interruptions, delays or setbacks. It is often used in the context of a project, plan or situation that is proceeding smoothly and according to schedule. For example, if you say that a construction project is "rolling along," it means that everything is going as planned and there are no major issues holding up progress. The phrase can also be used more generally to describe any ongoing process or activity that is moving forward without problems.