The photo shows it as quite a large ring around the camera lens and while it's white or transparent here the idea is that it will light up in different colors to alert you to missed calls or messages, with specific colors assigned to specific contacts.
But that's not all it can do. Smart Glow will apparently also be able to warn you of a low battery and perhaps most usefully help you line up selfies with the rear camera, by lighting up when it detects a face.
Apparently it's going to get better over time too, with Samsung adding new features like the ability for it to indicate the current weather conditions by lighting up in a specific color or even working with a heart rate monitor in some way.
Obviously with so many features attached to it the likelihood is that Samsung will put Smart Glow into more phones than just the Galaxy J2, and as a high-end handset the Samsung Galaxy S8 is a likely candidate. We may even see it in the Samsung Galaxy Note 7, though given that we didn't start hearing about it until recently it might be arriving too late.
In any case this shot of the Galaxy J2 (2016) gives us a good indication of how it might look in future phones, though it's possible that Samsung will slim the ring down, as it could prove a sore spot in the otherwise stylish design of its flagships.
Smart Glow hasn't yet been officially announced, so it's possible that these rumors and this image are inaccurate, but it's looking very likely and with the Galaxy J2 (2016) expected to be unveiled in India this week we'll know for sure soon. Then it's just a case of waiting for the feature to turn up on something more exciting.