
Yes, that old man was the Giver, he said that he was going to pass memories to Jonas. But like what memories? There were memories from a lot of generations, like from millions years ago. The Giver had to pass his memories to Jonas. To pass the memories they both had to grab their hands and the Giver would pass his memories. One memory was that Jonas was falling from a snowy mountain in a sled, when he finish he ask to the Giver why are no more mountains and snow, and the Giver said because hills was a waste of time traveling (all is flat) them and snow was difficult to build crops.
Jonas was surprised about the new memory he had about snow, hills and sleds. But he want more memories but for the Giver is exhausting to pass memories to another person, so Jonas insist and the Giver give him a memory about sunshine (it was a little painful to Jonas because the sun was burning his skin), when the memory finish, Jonas aced about sunshine. Why there is no more sunshine? Because it start burning, and "climate control" put a "fake" sunshine.