What is the meaning of ǀ?

the forward release of a dental click.

the tenuis velar or sometimes uvular dental click, [k͜ǀ] or [q͜ǀ]

[ǀ]-coloring or a weak, fleeting or epenthetic [ǀ]-release.

A letter of the Juǀ'hoan alphabet, written in the Latin script.

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

Source: wiktionary.org