I’m not wikipedia (but I did steal the last part from it) but Loli is an abbreviation of Lolita, both describe the same thing young, prepubescent kids, most often girls. It came about from a Russian-American book published in 1955 of the same name, Lolita, The protagonist and narrator is a French literature professor who moves to New England and writes under the pseudonym Humbert Humbert. He details his obsession with and victimization of a 12-year-old girl, Dolores Haze, whom he describes as a “nymphet”. Humbert becomes sexually obsessed with Dolores after becoming her stepfather, and romanticizes his obsession. Privately, he calls her “Lolita”, the Spanish diminutive for Dolores.