Concepts are ideas. Fine art conceptual photography builds from an idea that sets it apart from snapshots or landscapes. Conceptual photography expresses ideas rather then just presenting a documentary subject.
Snapshots of course are casual photographs taken without much thought. Landscapes photographs are finely arranged elements of the natural world but typically have little concept behind them other than presenting a pretty picture. There might be exception to the rule such as the work of the New Topographics movement, wherein the mark of man on the landscape is part of the concept. The idea is not to show pristine fakery but to show the world how it really has become, scarred by man. https://www.dogfordstudios.com/photography-as-art-new-topographics/
But concepts in a photograph start with an idea and then that idea is expressed with intent. Conceptual photography is a type of photography that illustrates an idea.
Here are some examples from my portfolio.
Pho Dog Grapher – Ground Glass View 
Revolver 
death skull flower 
Follow Your Dreams by Edward M. Fielding 
Smart Dog 