The Leonardo has 12 analog inputs. The first 6 are mapped on pins A0..A5 that you can read on the top of the board and are separated pins. The other 6 pins are named A6..A11 and are mapped on some other digital pins: you can see this on the bottom of the board.
Like the UNO, analog pins can be used like digital pins. So the Leonardo has 20 digital I/O lines (D0..D13+A0..A5) and 12 analog inputs (A0..A11). But, of course, you cannot use all of those pins at the same time, but it's correct to say that the board has 20 I/O lines: you just have 20 pins (14D+6A) on the top of the board free for use.