Vegeta isn’t just learning how to destroy something from existence, he is also learning to harness the enormous power of the destroyed item. This is only the early days but it looks rather similar to what a nuclear bomb does. By splitting an atom, something microscopic, enormous destructive power can be harnessed.
This is how Vegeta’s new power works and how Beerus, as well as every other God of Destruction’s power is sourced from. Vegeta can already vaguely do it but on a very small scale. It will be interesting to see if Vegeta can use this power in some way when Granola attacks.