we're gonna get quantum propaganda now!

AI can take your job even faster! Also eggs cost $50 now!

I don't understand anything about quantum computers. Are they useful? What do they do?

there's some quantum versions of algorithms that scale better than the digital version. ranging from quadratic to exponential speedup. Notably very fast at breaking currently widely used encryption.
We are only saved by the fact quantum computers don't have the required processing power to be feasible to use yet.

There's some encryption algos that are thought to be resistant against quantum attacks but due to the above this isn't actually proven yet, so currently any "post-quantum encryption" is currently a marketing buzzword with nothing behind it.

They're not a silver bullet, but they have their usecases. Quantum internet can be very interesting due to instantaneous communications. But for general purpose computing, a hybrid approach of quantum+classical is most probably the way to go. There's limited use cases for quantum computing in general computing.