What does “nature” mean here?
In this context, "nature" means the basic features or characteristics of something. In this video, when he says "the nature of the coronavirus" he talks about the infection rate, the place of origination. etc. This nature is different than nature that is outside such as animals, trees, plants, etc. Here are some examples of "nature" being used in the same context as the video: Ex: Cats are very independent. It's in their nature. Ex: It's her nature to be very shy and reserved. Ex: He ruled with an iron fist. It's in his nature.