This is a general counter for ten unspecified items or "ten pieces." It is typically used for counting a group of ten miscellaneous objects for which no specific counter is required, like "ten gifts" or "ten problems."

形(かたち)や種類(しゅるい)を問(と)わず、物(もの)を「十(じゅう)」数(かぞ)えるときに使(つか)います。プレゼント十(じゅう)、問題(もんだい)十(じゅう)など。