Hi,

The certification will contain functional questions in Odoo 16. To prepare for the exam make sure that you have functional knowledge across all the modules. 

Materials: 

Odoo Elearning: https://www.odoo.com/slides

Sample Certification:  https://www.odoo.com/slides/odoo-certification-sample-test-50

Odoo Functional Certification Exam: https://www.youtube.com/watch?v=Y9xCCLnSzzw

Thanks