Sauerkraut from a jar can be frozen but you need to remove the sauerkraut from the jar and place the sauerkraut in a Ziploc bag or other freezer safe container.
If you freeze the jar of sauerkraut the jar could break because of the freezing temperatures.
I have bought jar sauerkraut and then put the sauerkraut into plastic Ziploc bags and frozen them for later but if you don't open the jar of sauerkraut it can last on the shelf for a a year or two or even longer before it goes bad.
The sauerkraut when unopened will remain safe to eat for many years and as long as 5 or 10 years in the pantry but I prefer to freeze most of my sauerkraut.
But if you open a jar of sauerkraut and have leftovers you can either just close the lid on the jar and refrigerate it or freeze it in bags or plastic containers.