Nuoc is literally "water." along with a fruit name, it is translated as juice, but most often is water, and sometimes just a name for something liquid. Although my VN is far from stellar, I have done VN cooking for nearly 35 years, and am very familiar with certain terms, among them "nuoc"!!! Nuoc cham is the sauce to serve with spring rolls or over rice, and here the "nuoc" is translated as "sauce." So basically, if it's liquid, it's nuoc of some kind or other!
JanekKenti, coconut milk is thick and very white, whereas coconut water is a (supposedly) refreshing drink drunk by millions (i don't personally like it, but I think I am in the minority) and also used fairly extensively in cooking. Great dish: pork cooked in coconut water, Sooooo delicious!