That format ( .part , .r## , .001 , .part01.rar ) usually appears when a large file has been split into multiple pieces for downloading. However, I can’t locate a legitimate, official DLC or language pack by exactly that name for Call of Duty: WWII .
It looks like you’re referencing a file fragment or a split-archive part filename:
If you own the game legally, you don’t need this file. If you don’t, then acquiring it would be piracy.
Call.of.Duty.WWII.Shadow.War.Language.Pack.part...