This is a general counter for six unspecified items or "six pieces." Use this term when counting general objects that do not have their own specific counter, such as "six sweets" or "six chairs."

形(かたち)や種類(しゅるい)を問(と)わず、物(もの)を「六(むっ)つ」数(かぞ)えるときに使(つか)います。お菓子(かし)六(むっ)つ、椅子(いす)六(むっ)つなど。