Superconductors have two main properties that we think will be very useful.
The first is that they expell magnetic fields (Meissner Effect) which allows them to float when placed in a large magnetic field. This might have applications for magnetic levitating trains.
The second property is that they conduct electricity with no resistance, not a small resistance but none at all. This means that we can transfer energy with 100% efficiency. With normal conductors there is a small amount of resistance but it all adds up to mean we lose a lot of energy to heat. Superconductors would eliminate that.
Now, we've known about superconducters for over 100 years, but the problem is that in order for them to have those two properties they need to either very cold (-196°C/-320°F or colder) or under a huge amount of pressure (like thousands of times atmospheric pressure). Since it's not very easy to create these conditions, we can really utilize superconductors outside of particular settings (like a million dollar MRI machine).
The big news right now is that this new material (LK99 doped with Copper) was claimed to be superconducting at room temperature and pressure, conditions that are very easy to create. There have been similar major claims like this in the past but everyone of them so far has turned out to be false, so don't get your hopes up yet.
The difference here is that the papers shared a recipe for how to make LK99 very explicitly, which hasn't been seen before. This is allowing for other physics groups to make and test the substance to verify the claims of the original authors. So far, I don't think it's shown to be superconducting in the lab, but there are simulations that show it might behave as claimed. We have yet to see what will happen but we should know in a few weeks or months if LK99 is really what they claim.
Hope that helps. Let me know if you have any follow ups.
One thing to add, the original sample was theorized to be superconductive due to the magnetic levitation, not a measurement of it's resistance. In truth, "diamagnetic semiconductors" exhibit a similar levitation but without the lack of resistance; it's now theorized that's what the original authors experienced. The initial paper was also released with slim details, a lack of peer review, and a lot of unknowns. It's possible that "doped with copper" is nuanced, and if you made 100 samples of this with different doping at an atomic level, you would get different results. That would mean "LK99" is easy to make, but "LK99 doped with copper to exactly achieve superconductivity at room temperature and pressure" is NOT easy to make, and we may not even have the tech to dope it precisely enough to be useful.
The more likely outcome is research into a new doping technique which leads to material meta-science that could, one day, get a superconductor with practical properties. But this was sort of hyped as "a room temp/pressure superconductor that any mid-tier lab could make" which is just false...there are youtube science channels out there synthesizing the stuff and it's just not what was "advertised."