Glad you asked! We like the definition of sex-positive by the International Society for Sexual Medicine (ISSM) best:
“The term “sex positive” can be interpreted in different ways. For most, it involves having positive attitudes about sex and feeling comfortable with one’s own sexual identity and with the sexual behaviors of others. “
Wikipedia has a good one too:
“Sex positivity is “an attitude towards human sexuality that regards all consensual sexual activities as fundamentally healthy and pleasurable, encouraging sexual pleasure and experimentation.”