Yes you can freeze Kapusta.
Kapusta can be frozen and Kapusta freezes well.
It's best to vacuum seal the kapusta before freezing it as vacuum sealing the Kapusta keeps the Kapusta fresh longer.
However you can put the Kapusta in a regular Ziploc bag or freezer bag and it will keep just fine.
Or you can freeze the Kapusta in a regular food storage container and it will also be just fine.
Kapusta when frozen will keep for up to a year although it's best to eat the leftover Kapusta within a few months to 6 months at most for the best taste and freshness of the Kapusta.
When in the refrigerator the Kapusta will keep for up to 3 to 5 days at most but freezing the Kapusta will make it last longer.