At a guess they are talking about applications being built from the ground up to dynamically allocate resources using cloud providers APIs directly rather than relying on an assumption fixed resources are already provisioned and the application runs within them.
I wonder if I'm right ...
If that indeed is what cloud native means, it sounds interesting. But the problem is that all these APIs and especially "managed" services are super proprietary and you'll vendor lock yourself pretty hard. But I suppose that ship has sailed a long time ago.