Most planets are rocky, gaseous or icy and uninhabitable. Earth is one of very few planets which is covered mostly by water. In the case of Earth it is 72% covered by water (including 3% fresh water). Plus the poles is covered in ice.
However unlike Earth the planet "Kevin" is 6.5 times bigger than our planet (2.7 times bigger in diameter) and circles a small star about 42 light-years away. Depending on its composition its mass and gravity could be 4 to 6 times greater than our own.
Thus if life did exist there it would likely be short and squat, but very strong.
The planet is also partially steamy, so between the high gravity and steam any creatures living there would have to be extremophiles which can live in very hot temperatures.
Astronomers determined that GJ1214b is watery / steamy using the Wide Field Camera 3 aboard the Hubble Space Telescope which can measure a range of infrared wavelengths and can be used to estimate the planet’s composition. GJ1214b's atmosphere is at least half water and most of the water is on the planet’s surface in the same way the Earth has most of its water on the surface. The key difference is that GJ1214b's atmosphere is hotter and steamier.
The interior is unknown, but likely molten rock.