Johari can either mean jewel or essence in Swahili.
Same thing it means now: the language Swahili (Kiswahili in the language itself). It comes from the Arabic for coast.
"Xzavier" does not have a specific meaning in Swahili as it is not a Swahili name. Swahili names are usually derived from Arabic or Bantu origins, but "Xzavier" is not a common name in Swahili-speaking regions.
Naila (sometimes Nayla) is a common female personal name in Swahili, believed by this contributor to be from Arabic and possibly of significance in Islam.
It means 'angels' in Swahili and Arabic as far as I could find =D
Arabic
Arabic
Hussein is an Arabic name which is a diminutive of Hassan. It connotes "good", "handsome" or "beautiful."
It means "highest, most exalted one" in Swahili.
Swahili vocabulary springs from the Arabic language, made through more than many centuries of exchange with Arabic-speaking peoples
Bantu and Arabic primarily make up the Swahili language.
It does not have a meaning in Swahili, but it is an adopted Arabic name meaning "patient one".