Seeing that this is an example mod for Rift, I'm having trouble figuring out how this works. To be fair, I'm not familiar with Minecraft mod development with FML/Forge. And I'm not very familiar with mod development for mods that don't use Forge or FML, such as Rift and other loaders. I'm just having trouble understanding how this is supposed to work. Really, I'm interested in getting into modding with Rift, and I am having trouble figuring out where to start.

You mean in the code? That sounds reasonable.

For now, note that we are using Suppliers to create instances of anonymous extensions (child-classes) of the vanilla BlockSlab and BlockStairs classes that have a few overridden methods in order to make them directional like logs and make them strip-able.
Then we register the blocks and items.

All of the block models are done by hand and are in the same format as vanilla's blocks.
The reason that there's so many of them is that the combination of Stairs and directionality just creates hundreds of different states that a Log-Stair block can be in.