What is $1 dollar?

Excuse me, could you please clarify what you mean by "$1 dollar"? As far as I understand, the term "dollar" is a unit of currency, and when we say "$1," we are referring to one unit of that currency. So, essentially, when we talk about "$1 dollar," we're essentially saying "one dollar" which is a bit redundant. Is there something specific you're trying to ask about, perhaps in the context of cryptocurrency or finance?