Space exploration and investigation, while multi faceted, has essentially had an overall focus of one thing: finding life. As of now, while it is overwhelmingly likely that life does exist somewhere else in the Universe, we are the only planet we know of with life. One of the reasons for that, is to our knowledge, life requires water to survive. And this hypothesis makes sense due to the fact that all life on our planet requires water to survive in one way or another. Theoretically, there are infinite planets out there, meaning life could evolve in other ways, but as far as we know that is not how it works. This means that most of our focus on a potential life-bearing planet revolves around the existence of water. And scientists do not think they have found a planet with liquid water…until now that is.
The key to this is not so much that it is water – water as a vapor exists in a whole lot of places throughout the galaxy and universe – it is the fact that it is liquid water. Water vapor is more difficult to be utilized by life because it is a gas, and that makes it difficult to harness and utilize for habitation. But liquid water is concentrated enough to be to hold and support life. Early life on this planet lived exclusively in water for hundreds of millions of years, so to our understanding it is necessary for most life. Or at the very least, it provides very good conditions for life to develop and grow!
The discovery of this liquid water on an exoplanet does not guarantee life, but it is still a great step in our search for life. We may never know if this planet holds life, but at least it will hopefully tell us that there is liquid water elsewhere in the galaxy, meaning life as we know it could be more real than we ever thought possible.