A divorce is a formal ending of a marriage. It’s more permanent than a separation and involves a legal process. If you get a divorce, that means the marriage is officially over.
Divorce has both a noun and a verb form. The noun describes the thing you get — "you are getting a divorce." And the verb describes the thing you do — "you are divorcing your spouse." Divorce can also be used more broadly to describe any major separation. You might know of a politician who divorces himself from a controversial issue — that means he doesn’t want to be associated with it at all.