According to this site, buta appears to be the colloquial name of a "no pair". Is there such thing as a "no pair"? If not, what is it called in English?
According to List of poker hands, ノーペア is called "High Card" or "No Pair" in English.
Note that you may see some 和製英語 terms in poker and other Western-origin games. "Three of a kind" and "Four of a kind" are usually referred to as スリーカード and フォーカード, respectively, in Japanese. (Perhaps "-of-a-kind" was grammatically too difficult for Japanese people.)