What is the meaning of Twy?

this is…

O (vocative reference)

Unmarked for number and gender, but treated syntactically as masculine plurals when used with participles and relative forms, and as feminine singulars when referred to by resumptive pronouns.

Joined by n(j) to nouns they modify.

Used with suffix pronouns.

Originally joined by n(j) to nouns they modify; later without it.

Alternative form of twie

two

Source: wiktionary.org