What is an LTS version? It means “Long term support”. Basically its a version of software that the vendor commits to keeping secure and up to date but essentially freezes the functionality.
Why is a WordPress LTS important?
Well, some of us have developed some software that runs on WordPress or works with it and we depend on the present code base. New releases can break some functionality and if we’re managing say, 10 blogs for different people (therefore MU isn’t an option) it can be a big deal.