中彩 is a separable verb (离合词) meaning 'to win a prize in a lottery' — usually in a literal lottery, but also figuratively for a lucky break. It splits just like other 离合词: elements such as 了, 过, and 的 go between 中 and 彩 (e.g. 中了彩, 中过彩), and measure phrases fit there too (e.g. 中过一次彩). The word is colloquial and often used in the expression 像中了彩一样 to describe exceptional luck.