A bedstee was a bedstead. Typically, it was a closet in the kitchen or living room where people slept. At night, the doors would be closed to contain the body heat.
The bedstead would be short, typically less than 1.50 m/5 feet, since people slept upright. Some bedsteads had a shelf for a crib, or a drawer underneath the bed where infants would be put to sleep.
You may encounter bedsteads in estate inventories. Estate inventories are typically organized by room, which will show you whether your ancestors had separate bedrooms, or if they had bedsteads in the walls of the other rooms. More well-to-do families had bedrooms for the family, while the servants slept in bedsteads in the kitchen or attic.