iteration mark for repeating a kanji with its kun'yomi
A specific type of iteration mark (踊り字) shaped like 〻, used in vertical writing to indicate that the preceding kanji should be repeated and read with its kun'yomi. This is a technical term from Japanese orthography, not an everyday word.
The 二の字点 is a symbol used in vertical writing to repeat the previous kanji with its kun'yomi reading.
くの字点 is another iteration mark shaped like く, used to repeat two or more kana or kanji, whereas 二の字点 repeats a single kanji.
The name 二の字点 literally means 'the mark shaped like the character 二', referring to its resemblance to the kanji 二 (two). The mark itself is a simplified form of 二 used as a ditto mark in classical Japanese texts.