I am not able to move lights in Blender 2.8 in my MacOS. I place the light but I can't move it around, I've tried every key I could find.
Just so this question has an answer for anyone else who might find it:
Select the light in the viewport by left clicking on it - it should be highlighted in yellow.
press g, then move your mouse to move the object. If you want to move it along a specific axis, you can press g, and then press, for example, x, to move it along the x axis. if you want to moe it a specific amount, you can type the number of meters to move it after the axis of movement (e.g. G > X > 0.5 to move it 0.5 in the +x direction).