I do not understand how AHK should fill in the code in ().

;Replace them in the brackets after _IsPressed

Code:
Opt("MouseClickDownDelay", 50)

Global $IsPaused = False

HotKeySet("{F12}", "Script_Kill")
HotKeySet("{DELETE}", "Script_Pause")

Func Script_Kill()
Exit
EndFunc

Func Script_Pause()
$IsPaused = Not $IsPaused
EndFunc

While 1
If _IsPressed(0x06) And $IsPaused = False Then
Send ( "3")
Sleep(500)
MouseClick ("left", default, default, 3)
Send ( "4")
Sleep(600)
MouseClick ("left", default, default, 3)
Sleep(600)
MouseClick ("left", default, default, 3)
EndIf
If _IsPressed(0x04) And $IsPaused = False Then
MouseClick ("left")
Sleep(30)
Endif
WEnd


Func _IsPressed($sHexKey, $vDLL = 'user32.dll')
Local $a_R = DllCall($vDLL, "short", "GetAsyncKeyState", "int", '0x' & $sHexKey)
If @error Then Return SetError @error, @extended, False)
Return BitAND($a_R[0], 0x8000) <> 0
EndFunc