it's fine! we're alright with answering things like this! a system is someone with DID/OSDD/UDD (last two are only sometimes! they're umbrella diagnosis) , it's a result of repeated childhood trauma that leads a childs ego states to not form into a singular consciousness and identity, instead forming dissociated parts that later develop into alters.
in simplified words , someone with dissociative identities LAWL we're okay with elaborating if you're confused ... im not very good @ explaining me thinks.