1. in a frank, honest, or candid manner; with sincere and straightforward speech
Frankly, I don't think that's a good idea.
Francamente, eu não acho que seja uma boa ideia.
2. used to introduce a statement that is honest but may be blunt or unpleasant
Frankly speaking, your presentation needs improvement.
Falando francamente, sua apresentação precisa de melhorias.