Those with Windows 10 will recognise that phrase as it sits above the apps on their desktop.
For many people a photograph is a glance at life. Snapshots especially; though maybe 'a glimpse at life' suits their ephemeral quality more accurately. Then consider a selfie - that seems more of a glance at oneself, as if the camera becomes a mirror. Certainly I would consider some of my more esoteric photographs as askance glances at life. As if the camera was looking at the object being photographed out of the corner if its eye rather than full on.
The best 'decisive moment' photographs are glances at life that are suddenly magnified by time. They are glances that take hold in the memory because, as I have written elsewhere, they transcend the present and say something much more fundamental about human behaviour.
Life at a glance as Windows mean it implies that these days one's whole life waits for us to take hold of it each time we open our computer. However, hopefully, for most of us, life is much more exciting and rewarding away from the screen than sitting in front of it.