it is to allow you to run some linux tools under a windows linux emulator. you would not use it if you are not developing code or need a specific tool or app that only runs on linux. It will be slower than running on a native linux system on the same hardware.
it does allow you to skip setting up a virtual machine to run linux, or can save you from running two operating systems in a dual boot mode. or saves you from having a second machine to do linux type work.