If you install an app on your phone that Google doesn't know about, like an apk file that hasn't been scanned before. On install, it gets sent to Google servers, they scan it, then tell you if it's safe or not. With it off, it doesn't get sent to Google servers. I'd have it on
In other words, for the sake of keeping your phone and data safe, this option allows google to sample whatever apps you have on your phone. If you only download the app from Google Play or Samsung store, keep this option off. if you like to install apps from other sources that can be not so trustworthy, i.e., the app might hack your phone and steel your data, then keep this option on to let google check if the app is a safe one and trust worthy.