@BeHappy
It sounds like your friend is Transgender - though they may not identify with that word!
Here is some more information (that I put together earlier) about gender and transgender
Gender identity is a part of a persons personal and social identity, and refers to the way a person feels, presents and is recognised in the community as female and/or male.
Transgender and Trans are terms used to describe an individual whose gender identity does not align with the sex they were assigned at birth based on what their body looks like on the outside.
Gender identities are formed at an early age and are affected by many different factors, including what society values as the role and identity of being a male or female.
Many trans people will make changes to their body to better reflect their gender, and to be seen to the world as who they are. This might be achieved through medical treatment with hormones and surgery.
Some trans people will identify as male or female, but it is important to note that many people consider their gender identity to fall outside of the traditional (and limited) woman to man spectrum and may use other language to describe their gender.
People from Aboriginal and Torres Strait Islander communities have specific unique cultural experiences of gender, and use the terms Sistergirl and Brotherboy to describe this diversity of gender.
Many societies from around the world have more than two traditional genders, and will use culturally specific language to refer to this diversity of gender (e.g. Hijras of India, Khawaja sara of Pakistan, Fa’afafine of Polynesia, Kathoeys or ‘Ladyboys’ of Thailand, Two-Spirit people of North America Indigenous people)
Gender is independent of sexuality and so trans people may also identify as heterosexual, gay, bisexual,
People may use other words to describe their gender identify and experience of their gender, such as Gender Queer, Bi-Gendered, Agender, Gender Diverse,