An acronym standing for Lesbian, Gay, Bisexual, Trans, +. The + represents the countless other groups of sexual and gender minorities that would make the acronym too long for practical use.
This phrase is more commonly said as "LGB", "LGBT", "LGBTQ", or "LGBTQ+". In more complicated alterations, people refer to the community as LGBTQIAP. LGBTP stands for Lesbian, Gay, Bisexual, Transgender, Pansexual. The "P" in no way stands for pedo or pedophile.