In the United States, it is often used to describe adult education courses. These courses are offered as a kind of pastime or hobby to older people who are long out of school. People attend them voluntarily, for growth and enrichment.
The phrase "lifelong learning" suggests that everybody should be trying to learn constantly throughout their entire lives. It shouldn't be something that ends when you graduate from high school or college.
The phrase "lifelong learning" is often a part of the name of such programs. Some of them are connected with a foundation called the "Osher Lifelong Learning Institute." The courses offered are often short courses that explore a narrow topic in depth.
Some sample course titles I took from the University of Southern Maine's OLLI catalog include:
"The Symphonies of Gustav Mahler"
"Ethel and Zero and Mary and Rex: Great Moments in Musical Theater"
"A Taste of Hebrew" (introduction to the Hebrew language)
"International Auteur Cinema 12: Charlie Chaplin"