Combinig list program w/noob

hello all!

I'm kind of new to the programming world and have a challenge that i would like to realize, wondering if anyone could help ?

i have huge list files ( some are in the tens of gigs) that i have to combine and i have no idea how, i would need to check if there is no copies of one word in list, get the numbers in front of word in list out and if possible organize them alphabetically,

i have no idea of what I'm doing and wondering if anyone have suggestions with what language, and give me some indications of what to do or have a github maybe they could point me too or something ?

Thanks in advance for help !