Jahan, Jehan, Jihan, and Jeehan is a Central Asian word (Farsi, Kurdish, Turkish, Urdu, etc.) that means world, universe, cosmos, power, greatness. Turks spell it like Cihan.
It is used for both boys and girls, more for girls. It is not an Arabic/Quranic word but since the meaning is good Muslims can use it.
It is pronounced as (J)ump + beaut(I)ful + (HA)rd + (N)ame and and (JU)mp + (HA)rd + (N)ame. Both pronunciations are correct.
Ara is a Persian and Kurdish name for girls and boys that means adorner, beautifier, one who makes something prettier. It is not an Arabic/Quranic name but since the meaning is good Muslims can use it. It is pronounced as (A)rdent + (RA)n.
Araa, with a longer "a" at the end, is an indirect Quranic name whose details can be seen here: Araa
The difference between Ara (the Persian name) and Araa (the Quranic name) is that in Ara the beginning "A" is longer than the ending "a", while in Araa both the beginning "A" and the ending "aa" are equally long.
For names starting with S, please see this page which has a list of Quranic girl names starting with S: Looking for a nice baby girl name.