Note
As a beginner, opening theory doesn't really matter that much. Learn principles first. Also, I recommend that beginners stay away from modern openings.
For a reminder, opening principles are:
1. Gain space
2. Develop
3. Castle your king to safety. Don't castle if it'd make your king not safe.
A important part of becoming a higher rated player is knowing openings. The higher the rating, the more people use openings. Without knowledge of these openings, people will likely fall for the traps of these openings. So it's important to talk about them.