Even though the Galaxy S5 runs on Android 4.4 KitKat, it lacks the lockscreen widgets feature introduced by Google in Android 4.3 Jelly Bean. Samsung has not included any other similar feature on the Galaxy S5 as well, which is very much unlike its kitchen sink approach. Thankfully, if you have root access and are using Xposed framework on your Galaxy S5, you can easily reclaim lockscreen widgets using an Xposed module from developer goldie.
The Xposed module does not require any other kind of hackery. Simply download and install it from here, activate it from the Xposed framework app and then proceed to reboot your Galaxy S5.
When done, simply head over to the lockscreen, where you can now add or remove existing pages and widgets like it is possible on stock Android.
The Xposed module will not allow you to use lockscreen widgets if you are using a pattern or password on your lockscreen. In that case, install this Xposed module which works in conjunction with the first one, allowing S5 owners to use lockscreen widgets even with a secure lockscreen.