Prior to the initialization optimization, the numbers correlated with the things that needed to be loaded/grown and store assets had to be pulled from the Roblox website. The numbers indicates the regions not completed (top), the amount of trees needed to be grown (middle), and the amount of assets that needed to be rendered (bottom).
The text on the bottom of the GUI reads and operates as is. When the numbers all count down to zero, the GUI and its text will disappear and will now show the welcoming GUI. It is meant for the growth of trees (which grows at an accelerated rate, starting from a sapling and growing into adult stage in a matter of seconds), to prepare features ready for interaction (for example, the Boulders that fill up the entrance that blocks the passage to the Taiga), and prevent glitches.
A glitch that occurs when a player loads in their Land right after the initialization leaves players stuck on the waiting process when loading their base. The VIP Room may also fail to despawn, causing players to be able to claim the boxes if they load their base on it.