The Beach theme was released at the start of YoVille, by the original game developers, and was one of the first ever furniture lines. The basic set had a mixture of beach furntiure such as deck chairs, some beach decorations like seaweed and towels, and wicker furniture. There are a total of 37 items in this furniture line, including the beach wallpaper.
There was another theme in 2010, also called Beach. The two are unrelated and shouldn't be confused with each other.