This is the 63rd most frequent Portuguese word.
grande
Large; big; great.
Here, 'grande' emphasizes the significance/importance of the opportunity.
Essa é uma oportunidade grande para você.
This is a great opportunity for you.
In this case, 'grande' describes the physical size of the house.
Minha casa é grande e tem um quintal espaçoso.
My house is big and has a spacious backyard.
Here, 'grande' conveys metaphorically the impact or importance of the action.