Kenya is a rich and varied country, boasting: game parks, historical ruins, diverse cultures, and a bustling capital.
One Swahili word well known to most English speakers is 'safari', literally meaning 'journey'. It's also the obvious thing to do as a visitor to Kenya. There is no way to describe the feeling of being in proximity to a truly wild animal(although what makes them exciting can also make them a tad unpredictable, hence the first rule: listen to the guide). There are plenty of parks to choose from. In Hell's Gate, carved into the dusty Rift Valley, you are allowed to hike or bike through on your own, but if you'd prefer to be accompanied, try Amboseli, famous for its herds of elephants and the impressive sight of Mount Kilimanjaro rising in the background.
Kenya also has a large Muslim population, which adds an extra cultural dimension to the country. Lamu, the oldest inhabited town in the country, is almost entirely Muslim. It's fairly remote, but it's an atmospheric place to visit, there are plenty of interesting sights in the surrounding region, and it's increasingly easy for tourists to stay there(there's a general debate, of course, over whether tourism helps or hinders historic communities, but many would say that if you're conscientious and respectful you are doing more good than harm by being there).
The national languages are English and Kiswahili, and anyone planning to travel around will benefit from a familiarity with the latter. Of the 70% of Kenyans who are ethnic African there are a further 70 ethnic groups, many of whom will not be native English or Swahili speakers and will not necessarily know both languages. It won't be too difficult to pick up a few words, although getting fluent will take a little mental flexibility.
It's worth checking the advice on the Foreign Office site about Kenya, which, as with most holiday destinations these days, is not hazard-free. Generally speaking though, a degree of care and forward planning, and probably an organised tour, should in most cases be enough to banish any major concerns.