Bumblebee is a free software package for laptops with Nvidia Optimus laptops which have two different graphics cards sharing a single frame-buffer.
The goal of Optimus was to provide functionality allowing instant switching between the integrated Intel integrated GPU and a more powerful dedicated Nvidia GPU on laptops. This technology worked badly on Windows and the GNU/Linux experience was even worse. The bumblebee software project was an effort to improve the situation.
The Bumblebee software allows switching between the free Intel driver and the free nouveau driver for nvidia GPUs, it does not work with the Nvidia's own proprietary drivers.
The Bumblebee software project kind of failed in it's goal. It does provide a way to use both the Intel integrated graphics and Nvidia graphics on a laptop side-by-side. However, the way of "switching" is to prefix software which should be run using the dedicated Nvidia GPU with
optirun. That's simply not very user-friendly.
You should avoid buying a laptop with the Optimus technology.
However, if you do have one: Read the Bumblebee FAQ at https://github.com/Bumblebee-Project/Bumblebee/wiki/FAQ and learn how to use it. It is better to take advantage of hardware you have, however problematic, than to toss it away.