I definitely agree the articles related to bootloaders can be very hard to read
If you want to use GRUB and UEFI, my recommendation is follow the headings up until the end of Installation
https://wiki.archlinux.org/index.php/GRUB#UEFI_systems
Then you just need to generate the config
https://wiki.archlinux.org/index.php/GRUB#Generate_the_main_...
The partition you're referring to is explained here