The phrase "private deck" refers to an outdoor area or platform that is exclusively for your use and is not shared with others. It is like having your own outdoor space for relaxing, sunbathing, or enjoying the view.
Additionally, guests will enjoy access to the large private deck overlooking the mountain, private hot tub, 2 car garage and washer / dryer with additional refrigerator located on this level. (wyndhamvacationrentals.com)
It has its own private deck with spectacular views over the lagoon. (travelground.com)