transfer dvd win 10 iso image file to computer?

Hi,
- if have an iso file as an iso file on a DVD (i.e. simply data) it can be copied just like any file.
- if you mean you have a bootable Win 10 install DVD and you want to create an iso file from that, there are tools you can use.

However, every single build and language of Windows old and current is freely downloadable - see the relevant tutorial on downloading an iso file.

If you want the current (some might say somewhat buggy) build 2004, use the MS media creation tool (Google).

Note that there isn't an iso file specifically for Pro, rather the features made available depend on the registered activation of Windows held for that device on MS's servers, or, if clean installing for the first time on a device that has never previously run Win 10, on the key you provide.

There is no point in making backups as the ISO is always FREE from MS and its updated so there is no point in an out of date ISO

But as to point of .iso files, they are created from an original disc [or files used to create it] then downloaded to use with a program to create/burn an exact duplicate of that original disc when it is not available. Many copies can be made from that one file subject to any limitations of the copyright holder, usually no issue if made freely available. The file itself can be stored on a drive, can even use File Explorer's Mount to see the contents in it and sometimes run the install program.