municipality
The municipality, the local council that runs much of daily life: preschool and school, SFI and adult education, social services, elderly care, rubbish collection, libraries, local planning and building permits. Sweden has 290 of them, from big cities to small rural ones.
Your municipality is the one where you are registered in the population register. Part of your income tax goes to it, which is why the tax rate differs slightly between municipalities.
When something seems to differ from what a friend says, such as preschool rules or school holiday weeks, it is often because you live in different municipalities.