Android is basically a mobile phone operating system but many people prefer to install it on their PC to either have the same experience (playing mobile games on a bigger screen, for example) or in order to work on app development. You can install Android 7.0 on your PC using Android-x86 Project open source remix. As per the description present on the page, with this project you can port Android to the x86 platform.
This is a video that explains how to install Android 7.0 on your PC. This video is from Geektillithertz.com.