Rhythm and blues, often abbreviated as R&B, is a genre of popular music that originated in African-American communities in the 1940s. It has similar characteristics to other music genres including funk and hip hop but it is mostly associated with black culture. It is melodic and the beat is steady. The lyrics are usually sensual and they are mostly focused on love and sex. With R&BS, more focus is put on vocals than the lyrics.
Learn more on Wikipedia