Good place to learn about every option/button in Adobe After Effects?
The User Guide has all this information.

Online, visit the Adobe After Effects Help pages here and read the Animation and Keyframes section. As an example, the Track Camera page says:


  3D camera tracker effect
  
  The 3D camera tracker effect analyzes video sequences to extract
  camera motion and 3D scene data. The 3D camera motion allows you to
  correctly composite 3D elements over your 2D footage.