The loss number represents how close an AI model can reproduce an image.
The AI tries to build a model of a face by analyzing several images, then running iterations attempting to re-create those images. It tries over and over and makes improvements each time.
As a general rule of thumb, if your loss rates are 0.02 or below, you will see good results. If you notice your loss rates are over 0.03, it's likely there is a problem with your data (ie. more than 1 face detected). View our guide on Getting Better Results.