Laptop Specs says that Operating System is a Dos? Meaning No Windows?

I checked the specs of Lenovo B5080 2gb… It says that operating system is a Dos… What does it mean? Won't it install Windows?

DOS means Disk Operating System and was the first OS on home computers. Then came the first version of Windows which you loaded and ran on top of DOS. There's still a DOS type window in the Windows OS where you can type in commands but it is fast vanishing. If that is the only OS on that computer it must be old or they have come up with a new version of DOS.

Well windows is a DOS based operating system, and the B50s mostly come with Windows 8.1. So it may or may not come with windows, but it can be installed either way.

Windows can be installed on that Lenovo B5080

I think you're getting you terminology confused. DOS means disk operating system, and refers to ANY operating system that runs from and supports programs on disk. Windows, Mac OS, Linux, Solaris, Android, AmigaOS etc are all types of DOS.

The laptop will run Windows.