What is the meaning of Nt?

Alternative form of n/t (“no text”).

abbreviation of neurotypical

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

Neith, a primeval goddess of war and creator deity

alternative form of 'ant

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

abbreviation of inte (“not”)

initialism of như trên (“ditto”)

Source: wiktionary.org