Basically, they like to drink wine.
No. I'm kidding. WINE stands for WINE Is Not an Emulator, and it allows you to run Windows applications on a Linux machine. It's far from perfect, but it can be a lifesaver when switching from Windows to Linux. What user melpomenesclevage is trying to say, is that you can use WINE to significantly blunt the blow / daily usability learning curve when switching, to keep some of your familiar applications as is.
Edit: here's their site https://www.winehq.org/ the also explain it much better than I.