I want to know what version of PostgreSQL odoo 14 uses.

And I wonder if want to update PostgreSQL with new come up versions, will it affect on odoo server or the database ?

Odoo 14 supports Postgresql version 10.0 or later. and For more info please check the odoo documentation.

odoo 14.-0 documentation link :- https://www.odoo.com/documentation/14.0/setup/install.html