Symbolism, Imagery, Allegory
The Stone Table is an ancient Narnian monument—a slab of stone held up on pillars and covered in mysterious writing. But it's a pretty grim sort of monument: the White Witch and her Dwarf discuss the Stone Table as the proper place for traitors to be executed and sacrifices made.
And, at least for a bit, the White Witch seems to be 100% correct. Aslan agrees to let himself be sacrificed in Edmund's place, the Witch binds him to the Stone Table, tortures him for good measure, and kills him.
When Aslan is miraculously resurrected, though, thanks to the Deeper Magic from Before the Dawn of Time, the Stone Table cracks. Aslan explains that this, too, was part of a prophecy.
We can think of the Stone Table as symbolizing the normal laws of the universe—mundane old death-and-taxes stuff. But Aslan's sacrifice is so special that it breaks the Table in half forever. If you're really into Christian symbolism (like C.S. Lewis was) the cracking of the Stone Table reminds us of the veil in the temple tearing in half during Jesus' crucifixion and resurrection.