SaaS stands for "Software as a Service", this means that you are renting the software and you did not purchase it outright. It also tends to mean you don't have to install the software and keep it up to date because it is installed and maintained on a server that is owned by the vendor of the software rather than your own organization.
LMS stands for "Learning Management System". This is a type of educational software that allows you to create courses and lessons comprised of videos, documents, quizzes, and other materials for teaching someone a new skill or an important topic. You can learn a lot more in our article that talks more about what a SaaS LMS is.