Hello. I'm learning DirectX 12 API and I dont understand some things regarding Fences. The GPU can signal a fence while working on a Command List and then continues the command list or the Fence is signaled only between command lists in the List Queue ?

and then continues the command list or the Fence is signaled only between command lists in the List Queue ?

I don't really understand this part of your question but I'll try to answer.

A fence can be used one of two ways to sync the cpu to the gpu or to sync between two queues. The pseudo code for syncing two queues can be seen here: https://msdn.microsoft.com/en-us/library/windows/desktop/dn899217(v=vs.85).aspx

The syncing of the cpu to the gpu is easily seen in the D3D12HelloWorld example in the WaitForPreviousFrame() method of the hellotriangle project which can be found here:

https://github.com/Microsoft/DirectX-Graphics-Samples

If you can elaborate on your question maybe I'll be able to answer more directly. Also since D3D12 is new you might get more responses in the directx subforum.