LGBT stands for Lesbian, Gay, Transgender, Bisexual, and Queer. Here are the definitions and flags for them:
Lesbian means non men attracted to non men
Gay means you are attracted to the same sex/gender (not just men!)
Transgender people have a gender identity or gender expression that differs from the sex that they were assigned at birth.
Bisexual means attracted to two or more genders
Queer is an umbrella term that is both an orientation and a community for those on the LGBTQ spectrum.