Press your lips together to stop the air, then release. No vocal cord vibration.

Americans pronounce pbs as pee-bee-EHS (/ˌpiˌbiˈɛs/). Stress falls on the third syllable — keep everything else short and quick.
Record yourself saying "pbs" and play it back. The mic stays on your device — nothing's uploaded.
3 syllables, 6 sounds. Tap a syllable to jump to its row, then explore each sound's mouth shape and how it's made.
The textbook way isn't wrong — it's just not how anyone actually says it.
Stress falls on the third syllable, not the others. Stretch EHS — keep everything else short and quick.