svg-files are cutting files for a.o. Silhouette Cameo. I have made svg-files for my own appliques a few times. Not worth the effort if it is a one off, especially if you have to unearth your Cameo, but handy when you are doing multiples.
The new Husqvarna/Pfaff software lets you save the applique pieces as svg-files, which is a one click job, a new feature not available in 6D or earlier versions.
I don't know how easy it is to go from svg to pes - my software does not recognise svg, I would have to go to a drawing program first, save as jpg and go from there.

There is a facebook group called "Cuttin" it up with Cameo they may be able to explain in more detail. If you are not on facebook go to Forum at Embrilliance. They are very helpful. If you go to silhouetteamerica.com and go to page 98 of the manual it explains how it works. I am new to this and Hope this will be a starting point for you. The different machine companies are bring out cutting machine with this technology. Brother has scan and cut and Janome has one also. Also check out 'You Tube'

I have a Scanncut, and pictures are also format svg. It is to cut papers or fabric, it can be useful for applique. My machine numerize the pictures, and after it cuts. I do nor know if I I have explained for understanding to you