Firdaws literally translates to English as 'Paradise' & yes it's the highest rank in Jannah (heaven) It also means in the Arabic language a fertile land.

what i know like what u said the highest rank in Jannah in Islam or the wide orchard.

I noticed that the word "Paradise" sounds a bit like the word "Firdaws"فردوس ,so I looked up the origin of the word 'Paradise' and it turned to be of East Iranian origin,which means both the English and Arabic word originate from the East Iranian word. The etymology and meaning of the word according to Wikipedia : The word "paradise" entered English from the French paradis, inherited from the Latin paradisus, from Greek parádeisos (παράδεισος), and ultimately from an Old Iranian root, attested in Avestan as pairi.daêza-.[1] The literal meaning of this Eastern Old Iranian language word is "walled (enclosure)",[1] from pairi- "around" + -diz "to create, make". It subsequently came to indicate walled estates, especially the carefully tended royal parks and menageries. The term eventually appeared in Greek as ho parádeisos "park for animals" in the Anabasis of the early 4th century BCE Athenian gentleman-scholar Xenophon. Aramaic pardaysa similarly reflects "royal park". Hebrew pardes appears thrice in the Tanakh; in the Song of Solomon 4:13, Ecclesiastes 2:5 and Nehemiah 2:8. In those contexts it could be interpreted as a park, a garden or an orchard. In the 3rd-1st century BCE Septuagint, Greek parádeisos was used to translate both Hebrew pardes and Hebrew gan, "garden": it is from this usage that the use of "paradise" to refer to the Garden of Eden derives. This usage also appears in Arabic and the Koran itself as "Firdaws"

i think the lateral meaning is garden with fruits as you said. but i am not sure if it was taken from persian.