they began; they stood up
Ellos se pusieron a trabajar de inmediato.
They got to work immediately.
Se pusieron a hablar entre ellos.
They started talking to each other.
The girls started laughing.
Things got weird.
Todas las hojas del árbol se pusieron amarillas.
All the leaves on the tree turned yellow.
Se pusieron todos de pie al mismo tiempo.
They all stood up at the same time.
Everyone stood up.
Se pusieron en marcha los fuegos artificiales con una gran explosión.
The fireworks were launched with a huge explosion.
Ellos se pusieron en contra de Alemania.
They turned against Germany.