You can eat canned sauerkraut directly from the can without cooking it first.
The canned sauerkraut has gone through a fermenting process in the factory where it was made so it's ready to eat directly out of the can.
You can cook the canned sauerkraut if you want too but if you do cook the canned sauerkraut you kill the good bacteria known as probiotics which are what makes the canned sauerkraut healthy for you.
So if you cook the canned sauerkraut just note that the probiotics will not be there anymore and it won't be as healthy.
Canned Sauerkraut is best served directly from the can and onto foods after you've cooked them such as hot dogs, hamburgers etc.
Put the canned sauerkraut or any other sauerkraut onto the food after you cook them for best results.
But you certainly can cook the canned sauerkraut if you wan too.