Board Game Arena

Where is the value of cards and what is the Black square?

Are you sure you've understood the rules? What do you mean by "value"? The age number, assuming that is what you mean, is right on every card. I don't know what black square you mean.

I guess you mean the 'flavour' image on a black hex, which is different for each card and illustrates the card name..

This has no direct effect on gameplay, serving only to make the benefits of splaying a bit more varied (e.g.splaying right mostly gives you 2 useful icons per card, but sometimes just reveals one useful icon and a black image).