Complex sentence: William Felton "Bill" Russell (born February 12,1934) is a retired American professional basketball player who played center for the Boston Celtics of the National Basketball Association (NBA) from 1956 to 1969.
Split into simpler sentences: William Felton "Bill" Russell (born February 12,1934) is a retired professional basketball player from the United States. Russell played center for the Boston Celtics of the National Basketball Association (NBA) from 1956 to 1969.