No. बताना to tell बोलना to speak, to vocalize कहना to say, to call something बात करना to converse, discuss, have words with
Oddly enough, the word नहीं is not used with commands. One generally uses न or मत.
Although this has no bearing on learning the language: There is some theory by linguists, I believe, that नहीं is a contraction of न and है, kind of like "doesn't". न is the more elemental form of "no."
That would make a lot of sense, especially since often when sentences are spoken in a negative, है is often omitted
Indeed that would make a lot of sense. In Pali, a language of ancient India related to Sanskrit, "na" was already used as a negative (I don't know if there was any other word fulfilling that purpose actually). I would be very glad if any person knowledgable in Sanskrit or Pali could tell us more about this :-)