Unfortunately, it doesn't mean Macron will name a leftist prime minister. He already asked his center-right prime minister to remain in office for a while. But the message from the population is clear.
Actually he doesn't. That's what he should and kind of said he'll do, but he can shape the cabinet the way he wants. But he's no Trump so I dont think he will outrageously abuse this powers. I would'nt be surprised tho if decides to name a prime minister from his own party and offer some "key" ministy to the left, claiming the country is too divided to be managed by what he calls extreme parties. Or put in place some kind of technical government. Anyway you can't really trust him.