Here is what it means in detail
At the WWDC conference on Monday, Apple announced that the iTunes music service, released about 18 years ago, will be closed soon. In its place users will be able to use dedicated apps for music, podcasts and TV, in the same way as on the iPhone. The closure will take place at the time of the arrival of macOS Catalina, the new version of the Mac operating system.
The contents on iTunes will be automatically transferred to the dedicated apps, while for Windows there will be no change. Basically if you like iTunes you can continue to use it on Microsoft's operating system but we doubt that at this point someone could find a utility for it. We must admit that the software was rather inconvenient and anti-intuitive to use, and at least as far as we are concerned we have always preferred to keep multimedia files in simple folders on hard disks.
So will the death of iTunes be so important? No, and it is hoped that the management of music and videos on Macs can be simpler and more immediate. In any case, we advise you not to rely too much on digital downloads and content streaming services, preferring a more "ancient" approach. Why? Everything you buy digitally is not really yours but you are in practice purchasing a license to use the files on a specific platform or service. In a nutshell, if you want to avoid unpleasant surprises, make backup copies or stay in the retail market.