It is a lateral consonant. This means that this sound is produced by directing the airstream over the sides of the tongue, but not down the middle.
The manner of articulation (how the sound is produced) is fricative. This means that this sound is produced by constricting air flow through a narrow channel at the place of articulation, to make turbulence.
Former IPA letter for the voiced alveolar lateral fricative
In 1938, a letter shaped similarly to heng ⟨ꜧ⟩ was approved as the official IPA letter for this sound. It replaced ⟨ɮ⟩. However, the International Phonetic Association also suggested that a compromise between the two letters could be used if the author wanted. This compromise letter was included in the 1949 Principles of the International Phonetic Association and the IPA charts of that year. Although the International Phonetic Association said to use this letter, some authors still used ⟨ɮ⟩ from the 1960s to the 1980s. Later, this new letter was replaced by ⟨ɮ⟩ at the 1989 Kiel Convention.