Does the holy grail really exists? How far it is true... if yes means what does it specify..

What do you mean by th "holy grail" if you mean the cup used at the last supper? If so, of course there was one, does anyone know what happened to it, I doubt it.

There are all sorts of writings, ideas and beleifs, but no one knows.

Some even say that the "holy Grail" was Mary and she had Jesus child, but there is no proof of that at all.

And in fact, it really does not matter if there is or is not one still today, ( cup christ used) what really matters is that Christ lived and died for our sins and raised from the dead.