Learning CFrames is best done in projects. There are too many uses for them and you usually want it to do your thing. Those links will help especially the dev API reference and CFrame math article which I used for the following projects. However it’s best to look at them with a goal in mind.
My first project with CFrame, making a turret I had to get scripting support help for it initially thanks Moonvane.
My best current solution as a community resource check out the code if you are interested.
My second project is making a part orient to the floor using raycasting to make a unicycle in my attempt to create a weird vehicle.
Another more common project which requries CFrame is to use it for a building system like a furniture placement system.
I recommend doing a project you are most interested with and looking at that AlvinBlox tutorial which I looked at initially to get an overview of what it could do CFrame.lookAt is very important.