Secure Browsing :
Enable Secure browsing. When you enable this feature, your address http will be replaced by https which means secured browsing. Your password is safe in securing browsing. Always check for secured browsing means httpsfor other sites too like mailing, banking sites. Check the address bar and you will see, https instead of http.
Enable Email and text message notifications in this section. Once you enable notifications, every time you or anybody try to access your account, Facebook will ask for Device name through which you are accessing Facebook e.g. Work, Home . The benefit of this setting is that if someone try to access your account through some unrecognized device, you will be notified immediately through mail and text message, you can immediately check the security of your Facebook account.
You get the instruction to enter device name as shown in the screen shot.
Apps Passwords :
They are the one time passwords you can use to login to your apps. By this time if you are new to Facebook, you must not be knowing too much about apps. So we can skip this info and will try to discuss in the relevant article.
Recognized Devices :
As mentioned earlier, every time you log in to your Facebook account, you have to enter device name and it will be registered in the recognized devices section of security settings. You can store 100 device names at max. If you go beyond 100 names, you can remove names, by reaching here again.
Active Session :
This shows the login info which means the location from which you are logging in.