Wiktionary
funbox
n. (context skateboarding snowboarding English) A feature of a skatepark consisting of a tabletop connected to ramps and sometimes other features.
Wikipedia
Funbox
A funbox is a standard element of a skatepark. It generally consists of a box shape with a flat top and a ramp on two or more sides. A funbox may also include other elements that allow for more complicated skateboarding tricks.
Like other skatepark features, funboxes are used by skateboarders, inline-skaters and BMX-riders.