This means that we can use Unreal Engine 4 Level Editor on Mac ? Or only deployed games?

You will need a powerful setup to get started developing with UE4 right now. Here’s what we recommend: Desktop PC or Mac Windows 7 64-bit or Mac OS X 10.9.2 or later Quad-core Intel or AMD processor, 2.5 GHz or faster NVIDIA GeForce 470 GTX or AMD Radeon 6870 HD series card or higher 8 GB RAM