I suggest you visit a library or bookshop for a complete description of darkrooms, or try the articles in B&W World, the 'parent' of this forum.(posted 9305 days ago)However, here's a brief, specific answer.
You should distinguish between processing a film (ie just creating the negatives), and printing the negatives.
Processing a film requires complete darkness for about 5 minutes, just to load the film into the processing tank. The actual processing can them be done in light. By 'complete darkness' I mean zero light. You should not be able to see anything at all, even when you have been there for ten minutes.
B&W printing is done with a 'safelight', which is actually a low power bulb (e.g. 15 W) coloured red (or amber, or orange...). Ideally, there should be no other light at all. Switch off the safelight, and the room is in complete darkness. In practice, you can get away with a little leakage from door or windows, but this must be very low compared to the level of the safelight.