Questions & Answers about Nós temos uma boa ideia!
Why do we use uma instead of um here?
Wait, shouldn't the adjective go after the noun? Why is it uma boa ideia and not uma ideia boa?
Normally, yes! In Portuguese, adjectives usually come after the noun. But a few common, short adjectives are exceptions to this rule. The adjective for "good" (bom or boa) is one of them, so it usually goes right before the noun it describes.