As a linguist, languages intrigue me. I guess that is obvious. But as an immigrant, I understood the necessity to learn the local language. I also learnt how difficult that can be. Being Belgian, I had of course learnt Dutch and French in school. A privilege for sure (I am aware not all Belgian school-goers will agree with me at this age) because it concerns both a Germanic and a Romanic language. While travelling, I always have to explain that Belgium is split in parts and if I want to buy me bread in the one village, I do it in Flemish and if I go a couple of miles the other way, I need to order it in French. No biggie. Come to think of it, I also have to explain that Flemish is Dutch. Compare it to American and British English? But I digress..
When we arrived in Tanzania, we made an effort to learn Kiswahili. (By the way, the language is Kiswahili and not Swahili, sorry google translate.) I think it is only self-evident that as a guest in a country, you at least try. So we did the typical thing: started with some tapes (I am that old) and a book and as soon as you realize you are stuck, you take lessons. The advantage was that we needed it on a daily basis. The disadvantage was that Tanzanians are such a gentle people they wouldn't even think of correcting you so god knows what I said at times :).
Some interesting things about Kiswahili proved to be both fact and fun. Kiswahili mainly has an oral tradition: this languages has more often been used throughout centuries to sit around the fire in the village and tell stories than to write books. This is now of course no longer the case but for such a long time it was. So at times, I came across different spellings of one word or different uses of one word or different words for one thing. Theoretically, I guess you could say there are a lot of dialects.
Kiswahili is definitely a lingua franca, which means that for a lot of people it is not their first language but it a means to communicate with a lot of other people. If you read up on your history, it is of course because current countries and borders did not originate naturally, their were forced upon people, and often nomadic people that were asked to settle. Interesting stuff (in lack of many other adjectives that come to mind when reading up on history but not wanting to start a debate). This has consequences of course, since the way you tell your story contributes to the meaning: 'mtu yule' (the person over there) will be standing closer to you than 'mtu paaaaale' who is standing very far.
Kiswahili is a Bantu language, that means that for a European there are little to no reference points to study grammar or remember vocabulary. A conjugated verbform for instance gets a prefix which contains both subject and tense, and there are 9 noun classes, oh and also, if you want to refer to one of these noun classes as an object of your verb you insert yet again a letter into that verb.. So if you for instance want to say "I like him" that becomes ni-na-m-penda which very roughly stands for ni=subject I + na=present tense + m=object him + penda=verb root of kupenda. I am oversimplifying of course but believe me: it is an intricate language and I am sure I only ever spoke it in its simplest (often incorrect) form. But that simpler form is enough to get by, your effort will be appreciated. And the easy part for this Euopean: the vowels are pronounced as in Dutch (kinda).
The Swahili people inhabit a long line of coast, including islands such as Zanzibar and thus they came into contact with a lot of other tribes, peoples and nationalities. So today, the language is an incredible mix of languages and introduced words. The largest influence will undoubedtly be Arabic (tafadhali is please and salama is well, good) due to geographical reasons and a history of trade but there is also a lot of English (kabati is cupboard, closet, baiskeli is bicyle), and even German (shule is school) and Portuguese (nanasi is pineapple and chepeo is a helmet). And this is only what I can think of on the top of my head, I am sure there are more.
My children learnt Kiswahili as a subject in the international school, which is only normal since every international school teaches the national language, and their Kiswahili in the end became better than mine. Which is exactly what happened with their Spanish as well. At first, my evening school had me at a headstart but since their last two schools were in Spanish speaking countries, they now outdo me with ease.
My own students in Belgium often ask me: "so say something in Kiswahili!" But if you watched the Lion King, you can also say something: hakuna matata. If you ever travel to East Africa, you can get the T-sirt.