Unity units to pixel?

I am new for unity i have little confusion in unity units to pixel. Exactly 1 unity units = how many pixels? Anyone know help me.

1 unity unit is like one meter in real world. Imagine you making a photo of one meter skick. How many pixels in length it will be on your photo? it depends on distance from camera, from field-of-view (ie zoom factor), from your camera resolution and so on.

Yes, you can ajust settings and make 1 unit to match X pixels, but you will have layout problems on different screens, and you will have to solve them by using anchors, auto-layouts, and others. And X could be any number in this case, as you wish ant setup your project.