Scientists estimate that the body of water is a minimum of 1m deep and likely to be trapped under ice. Interestingly, it is deduced that the lake is composed of a high salt concentration, making it less likely that it will freeze. Highly concentrated brine lakes pose a decreasing likelihood of life "as we know it". That caveat is important, because, in truth, we don't know what life would look like outside of Earth, but its certainly promising news. It seems like liquid water was once present on the surface of Mars, but that is long gone...
Life, on Earth, has been found in extreme heat and chemical conditions (like around deep sea volcanic vents), where water plays a central role in bio-chemical processes important for life. "Extremophile" bacteria have now been found in highly acidic, alkali, hot, cold and more. Another example of wiidely distributed life is tardigrades (although admittedly much bigger and more complicated than simple single cell organisms!) and have been shown to survive cryogenic freezing for decades and even the vacuum of space! Theres no telling what or how life can vary since.... we just don't know what it could look like.
Satellite imaging techniques like these need to be refined and could help find more such bodies of water. Methane lakes, for example, have also been found on Titan, Saturn's largest moon.
Can we go to this lake?! It may be too far under ice for current robot technology and space delivery systems to tackle, although it seems like a real option for future Mars missions since water is the 'holy grail' of the signature of life 'as we know it'.
Do you think there is life outside of Earth? Answer in the comments!