A groovebox is like a hybrid, all-in-one production and performance tool. These potent bits of kit form an overlap between MIDI studio controllers, synthesizers, drum machines, audio interfaces, and samplers, and are designed for musicians and producers that are looking for a very specific yet very hands-on workflow. As such, there's actually no fixed definition of groovebox.
Usually, a groovebox will be a standalone music production tool loaded with some form of sound generator as well as a recorder/sequencer and can be used to create a wide range of different sounds. If you just want to make and sequence drum sounds, then a drum machine will give you everything you want.
A classic example of a groovebox is the Ableton Push. While it's just a controller - so designed for controlling software - the Push appeals to the groovebox producer because of its sequencer interface. Many grooveboxes also offer an MPC and/or x0x interface, where the MPC layout harks back to the vintage Akai MPC of the '80s which gave you a clear 2D grid of pads for triggering sounds. x0x refers to the step-time sequencers like the legendary Roland TB-303, TR-808 and TR-909 machines that formed the foundation of many EDM and hip-hop genres.
If you're looking for a groovebox that functions as a workstation, then it's worth bearing in mind that there are a lot of standalone systems and controllers out there. In principle, standalone systems won't require a computer since the unit itself is already a kind of computer. A controller on the other hand, can't do anything without a computer since it's literally designed to control DAW software. Often, good controllers will already come with DAW software packages included as standard.