can someone explain me the 3D rendering part?

[JanCantCode]

Ive been trying to understand how i am able to render 3D objects like Cubes etc. and after reading some of the rendering cod ein this project i am still very uncertain on how things work. from what ive read, you supply a VertexConsumer with Vertexes, which it then renders, and every tick, somehow all shapes are removed from the list of objects to render, and then readded, probaply to make sure the shapes turn with the player? I am quite confused and would love if someone would be able to explain how to do it a bit..