What is the meaning of 濁点?

a voicing diacritical mark, such as on , used to:

  1. derive the kana for a voiced-onsetted mora from the kana for a base voiceless-onsetted mora;
  2. orthographically convey a guttural tone, such as that of a cry or scream

derive the kana for a voiced-onsetted mora from the kana for a base voiceless-onsetted mora;

orthographically convey a guttural tone, such as that of a cry or scream

Source: wiktionary.org