Here's the key part of the prophecy:
"The one with the power to vanquish the Dark Lord approaches... born to those who have thrice defied him, born as the seventh month dies... and the Dark Lord will mark him as his equal, but he will have power the Dark Lord knows not... and either must live or die at the hand of the other for neither can live while the other survives... The one with the power to vanquish the Dark Lord will be born as the seventh month dies..."
It's important to note that the prophecy is spoken in a trance, induced by the presence of Lord Voldemort. This is why it's so fragmented and confusing, making it difficult to decipher at first.