become calm / less agitated or upset;
help someone become calm / less agitated or upset.
"He had just been trying to get her to calm down." - Staraliśmy się ją uspokoić
"Why are you so upset? Monica didn't intend to spill apple juice on you. Calm down!" - Dlaczego jesteś taki zły? Monika nie chciała wylać souk jabłkowego na ciebie. Uspokój się!
"I know boss is upset, but can you calm her down? She's making so much noise that she's irritating everyone in the office."