Japanese like to shorten words whenever possible so: Reso is Resort, just without the (rt). And Cha is Charter, just without the (rter).
This is another good example of Japanese shortening words:
All Nippon Airways - ANA. Japanese name is Zen Nippon Kuyu. But people in Japan calls ANA - Zeniku. The first two letters are taken from each word to create Zeniku, so everyone in Japan calls ANA zeniku, not Zen Nippon Kuyu.