"based" is a slang term that originated from internet culture, particularly associated with certain online communities. It generally means something that is authentic, unfiltered, or grounded in truth, often with a connotation of being bold or unapologetic. The term was popularized by rapper Lil B, who used "based" to describe a mindset of staying true to oneself, regardless of societal norms or criticism.
I had to look it up.