With those files you can start making your own scripts for GTA V PC or use scripts made by other people :)
The actual version of scripthookV works with game patch 1.0.335.2, so, to use it you may need to downgrade your gtav to this game patch, check how to do this in this video. ScripthookV works in cracked versions too, but the game patch must be the compatible one.
ASI Loader and Scripthook
This is the responsible for "hacking" the game memory and load the ScripthookV that will load .asi scripts, so, if you plan to use my .asi script mods you need this files.
Inside the zip file search for the files dsound.dll (or dinput8.dll for newer version) and ScriptHookV.dll, copy them to your GTA5.exe folder:
In newest version of ScripthookV they are using dinput8.dll instead of dsound.dll, so, if you have a dsound.dll from older ScripthookV, you need to remove it :)
Make sure that your game version is compatible, this version of ASI loader + scripthook works with GTA5.exe version 1.0.335.2:
This is a addon to the ScripthookV, it let modders use a C# and VB.Net languages to code the scripts, way easier and with OO that make script development easier and faster :)
Copy the files ScriptHookVDotNet.asi and ScriptHookVDotNet.dll to your GTA5.exe folder.
ASI Loader and ScripthookV by Alexander Blade
ScripthookV .NET by Crosire (and some other guys that i don't know now)
To start making your own .asi scripts for GTA V PC you need this SDK developed by Alexander Blade.
To make .NET scripts you need Microsoft Visual Studio 2012/2013 (maybe works with 2010 too). Add the ScriptHookVDotNet.dll file as Reference in the project, See the sample that goes with the files.
Required packages for .NET scripthook:
Microsoft .NET Framework 4.5
Microsoft Visual C++ Redistributable Package for Visual Studio 2013 (x64)