Sometimes it can happen that you have changed your Google password, and you do not remember what you have put, but what you had before. Or maybe you had an old password written down, but not the new one. The password recovery form asks you if you remember the last password you used on your account.
This first step does not solve anything for you beyond providing additional information to Google about whether it is you or not. If you remember the password, write it down and press Next, but if you have no idea, it is better that you press Try another way because a random word would only make you subtract points from what is your account.