Another "Earthlike planet"
Proxima b is actually interesting from one viewpoint -- it's the nearest extrasolar planet ever discovered. Its sun Proxima Centauri is part of the Alpha Centauri system, which is our own solar system's nearest interstellar neighbor. The two main stars in the system are Alpha Centauri A and B; they are fairly similar to our own Sun and orbit each other at a distance ranging from about one to three billion miles (one billion miles is about the distance from here to Saturn). Proxima Centauri is a much smaller and fainter "red dwarf" star orbiting the main pair at a distance of about one and a half trillion miles, which is one-quarter of a light year. It is currently between the main pair and us, making it the closest star to our Sun. The whole Alpha Centauri system is about 25 trillion miles (over four light years) from us.
(For context, 25 trillion miles is about seven thousand times the distance from Earth to Pluto, and it took the New Horizons space probe almost ten years to get to Pluto. "Near" is a relative term.)
Proxima b is similar in mass to Earth, though a bit larger, and it orbits within the "habitable zone" of Proxima Centauri -- the zone within which, if certain other conditions are met, the range of temperatures would be right for liquid water to exist. It is these features that prompt the designation "Earthlike".
We don't actually know much more than this about Proxima b yet, but a few things can be deduced. Remember, Proxima Centauri is a much smaller and fainter star than our Sun, so its habitable zone is much closer in. In fact, whereas Earth is 92 million miles from our Sun, Proxima b orbits less than five million miles from Proxima Centauri.
That is within the "habitable zone", but with such a small orbit, the "year' is only eleven Earth days long. More importantly, being so close in, the planet is almost certainly "tidally locked", meaning it keeps one side permanently facing Proxima Centauri and the other side permanently facing away, as the Moon is to the Earth. Half the world has eternal day, and half eternal night. Under these conditions the oceans, if they ever existed, must have long ago frozen solid on the night side and boiled away on the day side (ultimately ending up as precipitated snow on the night side), while the atmosphere, if there ever was one, would also have frozen out on the night side. It could be that more reasonable temperatures persist in a narrow ribbon of territory between the two hemispheres, but since the planet is probably airless, liquid water still could not exist there.
Numerous other factors can affect conditions on a planet -- Venus, for example, is similar in mass to Earth and only 25% closer to the Sun, but with its 900-degree temperature, its oxygenless air, and its atmospheric pressure about ninety times that of Earth, it is not remotely habitable to humans.
Earthlike planets may exist, but everything we know so far suggests that they are not common, and Proxima b certainly is not one.