What is the "something" in the story The Giver?Why was Jonas drawn to it?
You must be referring to the last scene of the book when Jonas, outside in the snow with baby Gabriel, feels drawn to advance a bit further in hopes of finding help.
This scene shows Jonas' intuitive nature, his ability to see beyond superficial things to get to the truth underneath. In the past it made him discover that people were hypocritical and that euthanasua was currently practised in his Community. Such a discovery led him to flee with baby Gabriel to save them both from the course of fate from which they otherwise would have no escape.
The ending of The Giver is hopeful but intentionally ambiguous as to the "something" out there, the "Elsewhere" just beyond. You will have to read Lowry's 'Gathering Blue' to find out more about Jonas in his new community (Yes, Gabe and he were indeed found and rescued!), but the information about him even there is scanty. Perhaps Lowry is cooking up another story which will bring the plots of her three previous dystopian novels (The Giver, Gathering Blue, The Messenger) together.