It's likely you're thinking of "buen" or "buena", which are the Spanish words for "good" or "well".
* Buen is the masculine form of the adjective.
* Buena is the feminine form of the adjective.
Here are some examples:
* Buen día (Good day)
* Buena comida (Good food)
* Buen viaje (Good trip)
* Buena suerte (Good luck)