What is the meaning of ɫ?

a velarized/pharyngealized [l], a dark l. (See ◌̴.)

[ɫ]-coloring, [ɫ]-release (of a plosive), or a weak, fleeting or epenthetic [ɫ].

A letter of the Heiltsuk alphabet, written in the Latin script.

A letter of the Kobon alphabet.

The twenty-third letter of the Lushootseed alphabet.

Source: wiktionary.org