Here’s a couple of great overview articles:
https://www.projectmanager.com/blog/10-project-management-knowledge-areas
https://blog.masterofproject.com/ten-project-management-knowledge-areas-pmbok/
The 10 knowledge areas are:
Integration
Scope
Schedule
Cost
Quality
Resources
Communications
Risk
Procurement
Stakeholder Engagement
The 49 PMBOK Guide Processes (45:09 minute video). This is a really good deep dive and well worth your time. Even if you only watch snippets, you’ll get a better idea of how project management actually works.