Shakespeare brilliantly plays on the meanings of nothing throughout this play. It can mean worthless, a person of little worth, or also mean everything, in the sense that much ado is made about everything. To note is to observe or mark carefully, something everyone in the play fails to do. It can also mean to stigmatize or point out, exactly what Claudio does to Hero in the church. Silence is something that Shakespeare always views with suspicion, and this play is no different.
Silence is actually worse than talking because it leads to plotting and conniving.
Indeed, it is soon obvious that silence is worse than talking too much, something that Beatrice and Benedick do. The danger of silence also affects the relationship between Hero and Claudio. Since they fail to talk with one another, they never resolve questions relating to the other's motives. Indeed, a crucial first mistake for Claudio is when he allows Don Pedro to speak to Hero for him, thereby creating confusion about Don Pedro's true motives. Don John is the evil bastard brother in the play.