This is the section of the official website where some of the main methods of Odoo are explained:
https://www.odoo.com/documentation/8.0/reference/orm.html
Of course, those are only a few compared with all you can find in the code. You will not find a webpage which explains all methods. The best way to learn Odoo is working with modules as an user and then reading the code to know how they managed to achieve the functionality.
solved Is there a Odoo function list? [closed]