Complex sentence: Janet Beaton, Lady of Branxholme and Buccleugh (1519--1569) was an aristocratic Scottish woman and a mistress of James Hepburn, Earl of Bothwell.
Split into simpler sentences: Janet Beaton, Lady of Branxholme and Buccleugh (1519--1569) was an aristocratic Scottish woman. She was a mistress of James Hepburn, Earl of Bothwell.