In the rural areas it is also used when approaching a compound to warn them of your approach (in case they were bathing outside or something). Some traditional houses don't have doors to knock on and it can feel very sudden to have someone appear outside your door when you live on a farm, far from others.
"can" instead of "may" is not accepted for this one. I wanted to report it, but the only options are: -The audio does not sound correct. -The dictionary hints on hover are wrong or missing. -The Swahili sentence is unnatural or has an error. It's definitely not one of these, but "can" should be accepted (as it is in all similar sentences in this course), how can I report it?