This was created by the BBC to encourage school children to learn to code. Every 12 year old was given one in their school. This demonstrated how seriously the government takes the view that the next generation should learn to code. However it is not for the exclusive use of children.
This is proving popular amongst hobbyists as you can now buy them. You can also borrow them from libraries for free, why not give it a go.
It is a small micro-controller about the size of a credit card. It has two buttons, a bunch of LEDs and a number of sensors and can be programmed using a scratch type coding language (called blocks) or Python (micro-python).
This is an excellent way to explore the world of the micro-controller. There are lots of projects available so you could start coding with blocks and progress to micro-python. The choice is yours.
There are a growing number of add-ons that you can buy to enhance the experience. From sensors to robots so you won’t run out of ideas quickly. To get started you can visit the official website or (I would recommend) downloading ‘code with mu’ and coding using that software, it is much easier.