The Installation Instructions for Windows page helps you to decide which install package to download. There are two packages for Windows available: 32-bit, and 64-bit. Which one to choose depends on what architecture of operating system you have: there are 32-bit and 64-bit Windows. So in case you don't know which one you have, the instructions tell you what to press on keyboard (it means, you need to press Windows key + Pause key), to see your operating system architecture.