Which rights and guarantees were secured by the fifteenth amendment to
the us constitution?

The 15th amendment states that everyone can vote no matter what their color, race, or servitude history was. This allowed slaves and African-Americans to vote.

the language dates from the contacts of arabian traders with the inhabitants of the east coast of africa over many centuries. under arab influence, swahili originated as a lingua franca used by several closely related bantu-speaking tribal groups.