You can play around with the UC GPA calculator to see what a B does to your GPA. https://rogerhub.com/gpa-calculator-uc/
The average UC capped weighted GPA for acceptance for UCLA is around 4.25. If you’ve taken the normal 5 a-g classes per year, that’s 20 semesters worth of classes for 10th and 11th grade. You have 6 APs so that is 12 semesters of honors. Your GPA with 1 B and the rest As is 4.35. 2 Bs is 4.30, and 3 Bs is 4.25. As such, one B won’t hurt, but more than 3 might hurt. Play around with the numbers.