Maid is a homebrew background for a character trained in household work, care, observation, and the quiet practical knowledge that comes from keeping people alive and a home functioning.
You were taught to serve and support a household. That may have meant cooking, cleaning, mending, hauling water, watching children, tending fires, preparing rooms for guests, caring for the sick, managing stores, or helping keep peace among people forced to live close together.
Household work taught you more than chores. You learned how people behave when they share a roof: who hides worry behind anger, who lies badly, who hoards food, who leaves tools where they should not, and which small changes mean something is wrong. In a longhouse, manor, inn, ship cabin, temple dormitory, or crowded family home, you know how to read the life of the place.
You understand how people are when they live together.
You have advantage on Insight or Investigation checks dealing with people who live together, or with a place where people live. This includes knowing where to look for a particular item, noticing signs of household tension, identifying who actually knows an answer, and knowing what to ask when seeking information.