Well there is two ways to give you what you need. The first code i sent you runs upon cell selection change. You can change that to run off of a keyboard shortcut if you want and have a separate code to run off of a different code to unhide when you want via a keyboard shortcut. Or if you just want to have a quick glance, you can keep the first code the same, and just make the unhide portion a keyboard shortcut. but note, that if you change your cell selection again, it will rehide the column if p2 is equal to 4. Make sense? but you could use this code to unhide
option 1: Keep the first code the same and use this to unhide your column via keyboard shortcut.
Sub Unhide()
'Keyboard Shortcut: Ctrl+h
If Range("O2").EntireColumn.Hidden = True Then
Range("O2").EntireColumn.Hidden = False
End If
End Sub
To assign to a keyboard shortcut, you just need to hit Alt+F8, highlight this macro and go to options. You can then select your keyboard shortcut that way.
Option 2:
Change the first code to this and assign that to a keyboard shortcut :
Sub HideColumn()
If Range("P2").Value = "4" Then
Range("O2").EntireColumn.Hidden = True
Else
If Range("P2").Value <> "4" Then
Range("O2").EntireColumn.Hidden = False
Else
Exit Sub
End If
End If
End Sub
Then use this to unhide via a keyboard shortcut as well:
Sub Unhide()
'Keyboard Shortcut: Ctrl+h
If Range("O2").EntireColumn.Hidden = True Then
Range("O2").EntireColumn.Hidden = False
End If
End Sub
These would provide you with quick keyboard ways to activate or deactivate your macros.