The World, numbered XXI (that's twenty-one in roman numerals), indicates that you are at an ending of a chapter, moving on to the next chapter, the next book. Feeling on top of the world, celebrating connection. Integrating previous experiences and lessons learned. Knowing your worth. Circle of life, one eternal round, alpha and omega, A and Z, 0 to infinity. Support from the four corners of the Earth.
If the World is in the obstacle position then it indicates that you may be having trouble integrating what you have learned and experienced. It could also indicate that you feel you know better than others and using that to bully others, likely as a misguided attempt to be supportive. Disconnected from the infinite, afraid of coming down, unrealistic "can do" attitude.
If the World is in the solution position it's a call to remember all that you have been through to get to where you are, and that where you are now is good. You're wiser, smarter, kinder. Every end has a new beginning. You choose how to end this chapter, and how to begin the next one. Trust your guides, trust yourself. Use the tools you have for the next jump.
NOTE: Picture slot intentionally left blank. No pictures are used so that anyone using any Tarot deck, especially one using the Smith-Waite system (aka: Rider-Waite-Smith), can use these meanings.