Hello I want to know can I run Witcher 3?

My spec.
AMD Radeon R7 260X 1GB OC (Sapphire)
Intel(R) Core(TM) i5 2300 2.80 Ghz Quad Core
Ram 4GB

Windows 7 64 bit

Also on what resolution and settings.

Thanks

You could probably play it at minimum settings and low fps (30 and below), regarding your CPU and GPU.
But your low RAM could be a problem. Adding 2Gb could help.