A Horcrux is a concept from the Harry Potter universe whereby a dark wizard/witch's soul is split into parts to make it more difficult to kill him/her. This format, from GitHub user kndyry, is one of two known implementations of a concept of file encryption and splitting inspired by this. (The other is Horcrux (jesseduffield).)
This form of horcrux is implemented in a shell script which encrypts a file and divides it into parts, or reconstitutes parts into the original file. Unlike the other form of horcrux, you need all the parts and the encryption key (password) to rebuild the original file; the other form let you build the file from a certain number (as specified upon creation) of parts which could be smaller than the total number in existence, and required no password or key.