Meaning 1 ►▼
Playbook is a book of strategies: a compendium of plays for the team, whether football or other sports. However, it is so common, that it is used in other speech, such as business and dating.
Please play defense according to the playbook.
Meaning 2 ►▼
A new playbook: New strategies for your plan, whether for business, college or a girl or boyfriend.
You need a new playbook for your new girlfriend.