Windows file names have two parts separated by a period: first, the file name, and second, a three- or four-character extension that defines the file type. In expenses.png, dxf, svg
If you don’t see file name extensions when you view files in File Explorer:
In the search box on the taskbar, type file explorer, and in the search results, select File Explorer.
In File Explorer under View, in the Show/hide group, select the File name extensions check box.
When you do this you will successfully see the file type extension.
but you will not see the SVG thumbnail; and this how you can see the SVG thumbnail on windows
First Download SVG Explorer Extension From HERE
Then setup it regularly
Finally you will see the SVG files thumbnail