“Can you explain that one more time?” feels embarrassing for a second and saves you hours of guessing.

Embarrassment is brief and guessing is long. The second you ask, you take a small hit to how competent you appear; the alternative is hours of quiet reconstruction with a decent chance of getting it wrong anyway. Most people asked to repeat something are glad to, because they would rather explain now than fix later. The exchange rate is absurdly in your favour.

Ask before the meeting ends or the person walks away, because the cost climbs steeply after that. Repeat back your version so they can correct the specific part that is off. Write it down while it is fresh.