The official language in Kenya is Swahili. Also common know and spoken is still English as an artifact of the colonial system of the British Empire. But not everyone in Kenya knows Swahili, in schools to learn Swahili is a must but every tribe has its own language, so especially in rural areas one still can find people who will understand neither Swahili nor English.
The pronounciation of Swahili is different from that of English, it's somehow similar to the pronounciation of German. The grammar is not that difficult, the most important structures are syllabels. Differnt syllables are responsible to make words, tenses and make possesive and reflective pronouns, together they make whole sentences.
Swahili is widespread in Kenya, Tanzania and Uganda, Rwanda, Burundi and parts of Malawi and Zaire. Today about 45 million people in East Africa talk Swahili.
If you want to learn more about the language check out the German - Swahili Online Dictionary at www.suaheli.eu.