There’s a lot of technicalities, you should absolutely start slow, at your own pace and work towards a goal. Don’t try to learn everything at once. It’s not possible (for most folks). Those topics are VAST.
To get started with the engine:
The Content Library has a search feature.
- Triangulation UV maps Normals Physically-based materials Color map Opacity map Emissive map Normal map
Intro to general PBR in UE4:
https://docs.unrealengine.com/en-US/RenderingAndGraphics/Materials/PhysicallyBased/index.html
and materials:
- Rigging Skeleton Skin weights Animations Animation state machines
- Lighting Static Dynamic
- Functions / Events
- Variables Local Global
- Collision Custom collision shells
- Custom console commands
- Audio Attenuation Reverb
https://docs.unrealengine.com/en-US/WorkingWithMedia/Audio/Overview/index.html
Check the menus on the left hand side for details / related topics.
- World space Local space
https://docs.unrealengine.com/en-US/Basics/CoordinateSpace/index.html