A long time ago a company named Kodak (remember them?) used to give tips on how to take better photographs.
One of the tips was to keep the sun over your shoulder. Like all advice in photography the advice may be good until it isn’t. Keeping the sun over your shoulder will ensure you have a flat even light. If you are just recording an object for scientific cataloguing, this front lighting, as it is called, may be perfect, but if you have people in the shot, they may end up squinting. Also, front lighting is usually the least dramatic.
Side lighting, where the light comes from, you guessed it, the side gives more depth and texture to your subject.
If you shoot a subject while you are facing the sun (or other light source) it is called back lighting. This tends to be the most dramatic, and sometimes the most challenging.
I noticed this image while wandering through Butchart Gardens while looking over my shoulder. A shaft of sunlight backlit the dark ruddy leaves and reminded me of a flame.