OP, you probably mean "Shamir's Secret Sharing Scheme". SSSS, as it's known, allows folks to split up their wallet recovery phrase into multiple parts called shares.  Rather than keeping that long string of words in one place, the shares let you spread the information around for safekeeping.  Some wallets build the scheme right in so splitting and recombining happens behind the scenes.  Takes the hassle out of managing the shares yourself, which helps avoid sloppiness.