In this context, a trope is kind of like a cliche in the sense that it’s always referring to some theme, scene, narrative element, etc. that occurs across various stories. The only difference is that a cliche is inherently popular or commonly used, but a trope doesn’t have to be. Basically, all cliches are tropes, but not all tropes are cliches.
So for example: the “chosen one” character archetype and a scene where the two leads confess their love right before the final battle would both be considered story tropes.