What is the meaning of Male-to-female?

Used other than figuratively or idiomatically: see male, to, female.

Transitioning or having transitioned (in gender identity or presentation, physically, etc) from being male to being female.

That changes a male end (with pins, usually a plug) of a connection into a female one (usually a socket).

A male-to-female transsexual or transgender person; a trans woman.

Source: wiktionary.org