A Link to the Past... What does it mean?

It's called that because it's a pun with Link's name and it is a prequel to the first two games.

The fact that Link is the Last in the line of Ancient Knights, the Pun on his name, it being a Prequel, all realy valid.

The fact that NoA couldn't use the original title is more telling, remind of the Dub of Mewtwo Strikes Back, they removed the all the references to God ruining the substance of the film.

It's not and never was a prequel.

America's Nintendo claimed it so, presumably to make sense of the name they decided to give it, to Miyamoto it has always been a sequel.

This was said in 1998 and then again in 2002 by an American employee admitting their mistake:

Dan Owsen:
The truth is, the text on the box (and possibly the Nintendo Power guide) is wrong. D'oh! If you just ignore the box text, the stories fit together better. Basically, the events in Ocarina are the "Imprisoning War" described in the SNES version's story. The Golden Land was the Sacred Realm before Ganondorf corrupted it. The order of the stories is: Ocarina, Zelda 1, Zelda 2, A Link to the Past.

I think...It´s because when Link goes to the Underworld,it is like a few years have pass.
And he can become to his time.
I think it means that.