Short answers, pulled from the story.
Swahili, also known as Kiswahili, is a Bantu language of the Niger-Congo language family. It was originally spoken by the Swahili people along the East African coast, primarily in Tanzania, Kenya, and Mozambique.
Estimates of Swahili speakers, including native and second-language speakers, generally range from 150 million to 200 million. Most native speakers live in Tanzania and Kenya.
About 40% of Swahili vocabulary consists of Arabic loanwords, drawn mainly from Omani Arabic, though some scholars put the loanword share lower. The name of the language itself comes from an Arabic word meaning "of the coasts."
The word Swahili comes from an Arabic name for the area meaning "coasts." It derives from sahil, meaning "coast," through the broken plural sawahil, to sawahili, meaning "coastal" or "coastal inhabitant."
Swahili became Tanzania's unifying national language after Tanganyika gained independence in 1961, when the government chose it to unite the new nation. The Tanganyika African National Union had already used it for pamphlets and radio broadcasts during the independence struggle, and it now unites over 120 tribes.
The United Nations declared Swahili Language Day as the 7th of July in 2022, based on Swahili's growth as a prominent international language. The date marks when Julius Nyerere adopted Swahili as a unifying language for the Tanganyikan independence struggle.
Swahili is one of three official languages, alongside English and French, of the East African Community. It is also a working language of the African Union and the Southern African Development Community, and Uganda adopted it as an official language in 2022.