Complex sentence: It was nicknamed a "Halfje", similar to the "Kwartje" (25 cent coin) and it was worth ½ a cent or 1/200 of a Dutch guilder.
Split into simpler sentences: It was nicknamed a "Halfje", similar to the "Kwartje" (25 cent coin). The coin was worth ½ a cent or 1/200 of a Dutch guilder.