A planet in the habitable zone could be Venus, Earth or Mars.
So far Keppler isn’t finding many Earth candidates...
In all fairness to Kepler, it only sees transiting planets which means their orbit has to be on a plane with the telescope. If you were looking for earth from a similar distance but from above, you wouldn’t find us.
Almost all of these planets are found in tight orbits around small stars. In this case the star is about one 1/3 the size of ours and the orbit of the planet is much closer and shorter. Again, if you were looking for earth from a similar distance, earth would only transit once every 365 days.