Complex sentence: Second-wave Feminism, also called The Feminist Movement, or the Women's Liberation Movement, is a period of feminist activity in the United States which began during the early 1960s and lasted through the late 1990s.
Split into simpler sentences: Second-wave Feminism, also called The Feminist Movement, or the Women's Liberation Movement, is a period of feminist activity. In the United States it began during the early 1960s and lasted through the late 1990s.