Windows 32-bit included NTVDM, to some extend also facilitating DOS programs to run. PC’s now come with Windows 10 64-bit installed, mostly without an option to downgrade to Windows 32-bit. Starting a DOS program will display a popup it can’t run…
That probably doesn’t help; The DOS application could be developed by yourself, a company not supporting it anymore, or out of business for years. Despite of Windows versions/alternatives, you may still prefer, even forced, using it for various reasons and time to come.

One option is to install a virtual Windows 32-bit system. The setup can be daunting, to 'only' run that DOS application, its use overkill and cumbersome. DOSBox is a popular alternative, but mainly intended for gaming.

vDos to the rescue. It lets DOS applications run by emulating a (spiced up) DOS PC in a window. vDos itself runs on Windows 32 and 64-bit systems, XP up to and including Windows 10.
If you however don't already use (still rely on) a DOS application, want to play with DOS or some game(s): Forget about vDos, it is not meant for you.
…Microsoft dropped 16-bit support (DOS is 16-bit) in Windows 64-bit, not just recently with Windows 10!
Some vDos highlights:
Start DOS applications instantaneously in a scalable window with a crisp TTF font (in text mode).
Focuses on serious programs (not games). Setup yours easily, no complex configuration to load drivers, set file handles, keyboard layout, language character set…
Run multiple DOS applications, if needed with their own specific configuration.
Print to modern Windows-only (GDI) printers, or a virtual printer to produce PDF’s.
Its file system is (in sync with) that of Windows, no internal disk caching corrupting files.
Network support with file- and record locking, also needed by multi-user DOS applications to function reliable.
Copy/paste text from Windows to DOS and vice versa, with transparent conversion of Windows/DOS text.
To find a version for your PC, check with the software publisher.
vDos is a Windows program to conveniently run DOS applications in all current Windows versions.
vDos by JHM Schaars - Zevenaar - The Netherlands - COC Arnhem 09103086