"LGBTQ"
Lesbian, Gay, Bisexual, Transgender, Queer/Questioning.

"Queer" is a catchall term for non-traditional sexuality/gender-identity. Questioning just means you aren't sure yet. Sometimes the acronym is LGBTQA, and the A stands for either Asexual or Allies ("Allies" meaning people who are heterosexual/cisgendered but are sick of seeing bigotry against non-hetero/cis people).

I've seen the acronym in about a dozen forms and the only part that seems to stay constant is "LGB". After that it's just alphabet soup. But the general meaning of it seems to get across.