I wouldn't even touch that file.
If it is in a folder called SOS Backup then I would assume that it is something to do with backup, but really, you cannot do anything with it until you can ask her.
Sorry to say I have little to go on here. On friends PC doing badly needed file sorting, duplicate deletions, etc. She has "SOS" Online backup. She is not reachable at this time, and I'm not able to view her settings, at least I've not found them in the program folder yet.
Regardless..... there is this SOS Backup folder in her My Documents folder. It has one single file ...... but over 20 GIG in size !!??
What could it possibly be for? There's numerous folders in the program folder that appear to be for database, and all sorts of things. The OS hard drive is only 75 G.! ( yeah, I know....... ) Even if it were 750G, I would still really question this 20G backup folder. After all,
it is an online backup application !