Ok, for example.
UIS = game.GetService("InputService")
UIS.InputBegan:connect(function(input)
if input.KeyCode == Enum.Keycode.KeypadSeven then
if arrowgui1 == true then
-- This gets skipped and just goes to the script instantly.
print ("Cannot go left")
end
end
end)

4 comments
it isnt being skipped. if its not working correctly then it isnt true.
yes, if statements don't get skipped...make sure the arrowgui1 value is what you are wanting it to be.
You haven't assigned a variable for "arrowgui1", therefore it can never be true.
please indent you code