When people ask how long paint takes to dry, they usually mean when they can use the room again. There are really three different answers.
Touch dry is when the surface no longer feels tacky. For most water based wall paints that is within a few hours, but the paint is still soft underneath.
Ready for another coat is the time the maker gives on the tin before a second coat can go on. It depends on the paint, the temperature and how damp the air is.
Fully hard takes much longer, often a couple of weeks. Until then, be gentle with the walls: no scrubbing, no sticky tape, and give furniture a little space from fresh paint.
Good airflow helps. Open a window where you can, and keep the room at a normal temperature. Cold, damp rooms dry more slowly.
All advice