Más means more. Nada más means no more. Your sentence needs context to make sense but means "One word not more or more" I think in English we would say, one word, no more or no less.

https://youtu.be/UuC77-xX4MY?list=PLA5UIoabheFMo9oB_AF7JftV34ecOalvM 1.39 You can check the context here :)

Valeriya, could you please provide more information about 1) the context of the sentence and 2) what is it exactly that you understand or do not understand. The expression "nada más" means "nothing else", "más" means "more". But depending on the context they may express different ideas, or they may have to be expressed differently in English or Russian. For example: "no quiero nada más", "I do not want anything else" or "I do not want anymore" (it will depend on the context), "я не хочу ещё" или "я не хочу другой" (again, depending on the context).

If you are holding a conversation in spanish or listening to a speech and you want to add a little idea before finish it, you can say: "una palabra nada más".