The family (partner) visa is for the husband, wife, civil partner or unmarried partner of a British citizen or someone settled in the UK. It is a five-year route to settlement, with a relationship test, a financial requirement and a rising English requirement.
You usually get permission in two stages of around 2.5 to 3 years each. After five years, and once the English and Life in the UK requirements are met, you can apply for settlement. Some applicants are placed on a longer ten-year route.