Keybinds helps players for having an easier gameplay. Macro / Keybind Mod let you set a shortcut for one command or more. This mod was released because vanilla minecraft doesn’t has those features.
Would you like to know some about the features? Well, it is very easy to use because you don’t have to memorize any names or key codes, just bind whatever you want. You can overwrite the actual keys like WASD. Also you can have different keybinds on different servers. You can create scripts like auto walking, sprint, toggleable sneak. And at least you can create custom GUIs which let you create instant game menus.
So, in conclusion, if you are tired of finding your commands or whatever else you want to find, now you can only bind the command and use it right away.