https://www.bleepingcomputer.com/news/microsoft/optional-cumulative-update-kb4457139-for-windows-7-released-with-bug-fixes/

After releasing new cumulative updates for Windows 10, Microsoft is also rolling out a new patch for Windows 7. The KB4457139 is now available for Windows 7 via Windows Update and Microsoft's Update Catalog. Windows 7 KB4457139 is an optional update and it includes improvements and fixes that were part of the KB4457144.

According to Microsoft's support document, KB4457139 for Windows 7 comes with non-security improvements and fixes that are aimed at enterprises and businesses.