Complex sentence: Football is the most popular Sport in the Netherlands, was introduced to the Netherlands by Pim Mulier in the 19th century when in 1879, at the age of 14, he founded Haarlemsche Football Club.
Split into simpler sentences: Football is the most popular Sport in the Netherlands. Football was introduced to the Netherlands by Pim Mulier in the 19th century when in 1879, at the age of 14, he founded Haarlemsche Football Club.