This way you get very strong password which you don't need to remember, because next time you can calculate the same password here.
The password encoding process runs locally in your browser using javascript, your data is not sent anywhere.
In "Advanced Options' you can select the password length, specific seed (index) used during password calculation, and algorithm version (see. Changelog)
v1.1 - Password is aditional to v1.0 enhanced to contain at least 2 small letters, 2 big lettets, 2 numbers and 2 special characters.
v1.0 - Password is generated as portion of the base64 encoded sha512 hash of the password phrase.