Swahili is part of the Bantu group of languages which stems from the Niger-Congo language family. It was strongly influenced by both Arabic and Persian, as is evident from the many words of Arab and Persian origin found in the Swahili language today. Even the name "Swahili" comes from an Arabic word meaning "by the coast."
While there are hundreds of languages in East Africa (more than 120 only in Tanzania), the most popular languages tend to be Swahili and English. English is usually the language of business, while Swahili is the national language of both Kenya and Tanzania. There are Swahili speakers in most of the surrounding countries, including Congo, Uganda, Mozambique, and it's one of the widely spread languages in East Africa, with more than 50 million people speaking it.
Some East Africa countries, however, do have a better command of English. For example, in Kenya and Uganda, most people in the urban areas can usually speak English. Generally, people have a good command of English, and are very gregarious. Conversely, in rural settings, and in most places in Tanzania, most locals speak Swahili or their local language.
While most people who deal in the tourist industry speak English, learning some basic Swahili greetings and answers, will help you tremendously and earn you much more respect.
You can begin by learning some of the basics - important words like "thank you," "how are you," "yes," and "no." There are tons of excellent resources on the Internet that will advise you which basic Swahili words to learn, how to construct a simple sentence, and what to say if you have a problem. Transparent Language's Languages of the World is a great way to learn Swahili. This multimedia Swahili software program enables you to hear, read, and speak Swahili. Anyone - even complete beginners - can start speaking basic Swahili almost immediately with this unique learning system.
Although Swahili might sounds difficult, it's phonetic and easy to learn.
But be careful! Don't assume that a Swahili word always means what you expect. The word "leo", for example, doesn't mean "lion." It means today. And "bin" does not mean "container;" it means "son of". And don't think the word "kiwi" is the name of a fruit-- it means "to dazzle".
One of the most difficult aspects of learning basic Swahili is its system of nouns. Nouns in Swahili are divided into cases based on the way that they are spelled. There are sixteen noun cases in all! But don't worry - that includes singular and plural.
You might be perplexed at first by the way that time is expressed in Swahili. In the Swahili culture, there are two 12-hour cycles each day. The day cycle begins at sunrise (approximately 6:00 AM) and ends at sunset. The evening cycle begins at sunset (approximately 6:00 PM) and lasts until dawn. So 8 AM is expressed in Swahili as "saa mbili asubuhi", or literally "two o'clock in the morning." At noon, it is "saa sita", or "six o'clock."
Remember, it's okay if you make mistakes when speaking. A traveler will learn much more if he is not afraid to speak and make mistakes. Usually everyone laughs and the local tries to show you where you were wrong and correct you.
Thus, it remains only to wish you the best of luck in your endeavor to learn Swahili.