They say they did a computation on a ca 100 qubit chip much faster than a conventional (super)computer could do. The particular calculation in question is to produce a random distribution. The result of this calculation has no practical use.

They use this particular problem because it has been formally proven (with some technical caveats) that the calculation is difficult to do on a conventional computer (because it uses a lot of entanglement). That also allows them to say things like "this would have taken a septillion years on a conventional computer" etc.

It's exactly the same calculation that they did in 2019 on a ca 50 qubit chip. In case you didn't follow that, Google's 2019 quantum supremacy claim was questioned by IBM pretty much as soon as the claim was made and a few years later a group said they did it on a conventional computer in a similar time.

So while the announcement is super impressive from a scientific pov and all, the consequences for everyday life are zero. Estimates say that we will need about 1 million qubits for practically useful applications and we're still about 1 million qubits away from that.