From Arabic مَرْحَبًا (marḥaban).
1) The correct response of a superior after his/her inferior says shikamoo.
Shikamoo: A shortening of -shika miguu ya ("to fall at one's feet").
I see a lot of people discussing how Swahili borrows a lot from Arabic in these threads. I just want to point out that Swahili also borrows from Congo-Niger languages like Kikongo, unfortunately not taught here on Duolingo. I feel the need to say this because I don't see these "Oh, it's just like Arabic!" comments in the English, Spanish and French sections, even though these other widely spoken languages also borrow many words from Arabic. No, most people don't know that, either. It is a shame that there still isn't another African language here, because this one East African trade language truly isn't enough to showcast the rich diversity of African languages to the rest of the world.
I HOPE they will teach one of the 'click' languages. In being fascinated by Laurens VanderPost on his life in South Africa and about his being raised by a Bushwoman, I am captivated by the click languages. .Wow, look what i found~ https://www.youtube.com/watch?v=2Mwh9z58iAU&feature=youtu.be MIriam Makeba! 5 different clicks she teaches us before she sings!
But "Marahaba" doesn't mean "I accept your respect." That would be "Napokea heshima yako," iirc. Marahaba is an untranslatable greeting. As such, the most straightforward way to translate it into English is, "Hello." (And then you have to understand that its only usage is in the specific context where you're responding to somebody who has just said "Shikamoo," which is another untranslatable but highly contextual greeting.)