This is the 8862nd most frequent Portuguese word.
aproveitem
"Take advantage" or "enjoy" (command/plural form).
In this sentence, 'aproveitem' is used as a command urging the listeners to take advantage of the sunny day.
Aproveitem o dia ensolarado para passear no parque.
Enjoy the sunny day to stroll in the park.
Here, 'aproveitem' expresses a wish that the listeners take advantage of the special offer.
Espero que aproveitem a oferta especial na loja.
I hope you enjoy the special sale at the store.
The word 'aproveitem' in this context encourages the audience to cherish and take full advantage of the celebratory moment.