Roads of Luoyang

洛陽道 (儲光羲)
大道直如髮
春日佳氣多
五陵貴公子
雙雙鳴玉珂

Luo - Sun - Road (Chu Guang Xi)
Big - Road - Straight - As - Hair
Spring - Day - Excellent - Weather - Many
Five - Mound - Noble - Public - Son
Pair - Pair - To Ring - Jade - Ornament on a Bridle

Roads of Luoyang (Chu Guang Xi)
Main roads as straight as hair
Many spring days with excellent weather
Noble sons of officials of Wuling Hills
Riding side-by-side the jade ornaments on their bridles ringing

About plurality: Chinese words don't generally have a distinct plural form. Sometimes you just have to infer the plurality from the context.

五陵: Wuling Hills. If you are not lucky enough to find the dictionary entry for the names of places, then you just have to rely on someone telling you.

雙雙: This means, "in pairs". Since this poem is about the young lords on the main roads of a city and because of the reference to the jade ornaments of bridles, it would make sense that they are riding horseback side-by-side or in pairs.