explain the code below


I_Icon = C:\Users\user\Bluetooth.ico
IfExist, %I_Icon%
  Menu, Tray, Icon, %I_Icon%
;return

#NoEnv
SetWorkingDir %A_ScriptDir%
#SingleInstance Force
#include gdip64.ahk
global g_gdi_token := Gdip_Startup()
OnExitGdipShutdown() {
    for k,v in bitmaps
        Gdip_DisposeImage(v)
    Gdip_Shutdown(g_gdi_token)
}
global QPF := 0
DllCall("QueryPerformanceFrequency", "Int64*", QPF)
QPF /= 1000
GetTime() { ; milliseconds
    static start := 0
    static counter := 0
    DllCall("QueryPerformanceCounter", "Int64*", counter)
    start := start ? start : (counter / QPF)
    return counter / QPF - start
}
PrecisionSleep(period)
{
    if !(error := DllCall("winmm\timeGetDevCaps", Int64P, TimeCaps, UInt,8)){
        MinSetResolution := TimeCaps & 0xFFFFFFFF
        DllCall("Winmm.dll\timeBeginPeriod", UInt, MinSetResolution)
    }
    if (period >= 0)    
        DllCall("Sleep", UInt, period)
    if (MinSetResolution)                       
    	DllCall("Winmm.dll\timeEndPeriod", UInt, MinSetResolution)
    return error
}	
GetFPS() {
    static UPDATE_INTERVAL := 1
    static timeLast := 0
    static counter := 0
    static fps := 0
    now := GetTime() / 1000
    if ((now - timeLast) >= UPDATE_INTERVAL) {
        fps := Round(counter/(now-timeLast),1)
        timeLast := now
        counter := 0
    } else {
        counter++
    }
    return fps
}
; #include <common>
; #include <memoryClass>
; #include <errors>
OnExit("OnExitGdipShutdown")
#InstallKeybdHook
#InstallMouseHook
#UseHook On
#KeyH Write exactly 6 paragraphs each separated with two new lines answering this question. The first paragraph must start with "protect".
user