Zhuangzi - Kingly rewards

宋人有曹商者為宋王使秦其往也。得車數乘；王說之，益車百乘。反於宋， 見莊子，曰：「夫處窮閭阨巷，困窘織屨，槁項黃馘者，商之所短也；一悟萬乘之主 而從車百乘者，商之所長也。」莊子曰：「秦王有病召醫，破癰潰痤者得車一乘，舐 痔者得車五乘，所治愈下，得車愈多。子豈治其痔邪？何得車之多也？子行矣！」

宋人有曹商者為宋王使秦其往也
A man of Song, named Cao Shang, serving as an ambassador of the king of Song to Qin, was leaving the country.

宋人有曹商者 Among the people of Song, there was someone named Cao Shang
宋 Song, a state
宋人有A者 : among the people of Song, there was someone who A
秦 Qin, the state
使 a messenger, an envoy, or ambassador
為 to be, for, on behalf of
王 king
為宋王使秦 He was sent by the king of Song as an ambassador in Qin
往 to go
其 is used here to remind the subject (Cao Shang), after the complement 為宋王使秦 : Caoshang, having been named an ambassador of the king of Song in Qin (為宋王使秦), he (其) left (往).
Note : my reading of the beginning of this passage is different from the punctuation found in many modern editions, which goes
宋人有曹商者為宋王使秦。其往也，得車數乘；王說之，益車百乘。
The 其往也， is put at the beginning of the second sentence. I believe this is illogical, as this is an instance of 有A者B也, and 也 is usually not found in the middle of sentences.I therefore chose to read it as 宋人有曹商者為宋王使秦其往也。得車數乘；王說之，益車百乘。and adapted the punctuation accordingly...

得車數乘 ;王說之 , 益車百乘。 He had but a few chariots, but the king (of Qin) was pleased with him, and gave him one hundred chariots.
得 to obtain, to own
車 chariot
數 several, usually implying a small number
乘 a team of horses
In classical chinese, numbers (and specificatives) are often put after the noun : Modern chinese :百乘車 one hundred chariotsClassical chinese : 車百乘 one hundred chariots
說 to like, to be pleased with someone
之 him (complement)
王說之 the king liked him
益 to increase, more, the verb (to give more) is here implied.

反於宋， 見莊子，曰：When he returned to Song, he visited Zhuang Zi and said :
反 to return
見 to visit, to pay a visit
莊子 Zhuangzi

夫處窮閭阨巷，困窘織屨，槁項黃馘者，商之所短也；一悟萬乘之主 而從車百乘者，商之所長也。Living in a poor house, in a narrow alley, being utterly poor and wearing sandals of woven straw, this is what I call bad. To be a confident to the ruler of ten thousand chariots, and have an escort of one hundred horses, this is what I call great.

夫 in spoken language, introduced an explanation : now, as a matter of fact
短 small, bad, to consider bad
長 long, great, to consider great
所 makes what follows a relative :
所短 what is short
商 I, Shang
商之所短 this is what I Shang, consider bad (short)
商之所長this is what I Shang, consider great(the 之 adds emphasis on the sentence : *this* is what I consider …)
The whole sentence therefore is 夫A者，商之所短也；B者，商之所長也。Now, A is what I consider bad, and B is what I consider great.
處 to live in some place,
窮 extreme poverty
閭 a house in a village, a small village
阨 narrow, poor
巷 a narrow (and poor) alley
處窮閭阨巷 living in a poor house, in a narrow alley
困 poor, narrow
窘 lack of resources, poverty
織 cloth, weave
屨 shoe, sandal
困窘織屨 living in poverty and weaving sandals (out of straw)/ or having sandals made of woven straw
槁 dry, skinny
項 neck
黃 yellow
馘 literally cut the head (or ear) of a prisoner of war, here, it probably means the face
槁項黃馘 skinny neck and yellow face, ie having a sickly face on a skinny neck
一 one, the only one
悟 to understand, to be in the good graces of someone
主 ruler
萬乘之主 the ruler of ten thousand chariots
而 and
從 to escort, an escort
從車百乘 to have a escort of one hundred chariot

莊子曰：「秦王有病召醫，破癰潰痤者得車一乘，舐 痔者得車五乘，所治愈下，得車愈多。子豈治其痔邪？何得車之多也？子行矣！」Zhuangzi said : « When the king of Qin was ill, he summoned doctors. Those who punctured his abscesses and emptied his furuncles were rewarded by one chariot. Those who licked his hemorrhoids received five chariots. The dirtier their healing, the more chariots they received. Did you by any chance heal his hemorrhoids? How come you received so many chariots? Get away of here! »
病 illness
有病 to be ill
召 to call upon, to summon (someone in a higher position calling upon someone in a lower position)
醫 doctor
破 to break
癰furuncle, abscess
潰 to flow (for a river which breaks its banks and floods)
痤furuncle
者 makes what preceeds a noun
破癰潰痤者 those who broke his abscesses and emptied (flowed) his furuncles (yuck !)
得車一乘 received one chariot, was rewarded with one chariot
舐 to lick
痔hemorrhoids
愈 … 愈 the more …. the more…
治 to heal
下 low, meaning here dirty
多 many

所治愈下，得車愈多 the lower they healed, the more chariots they received
子 you
子豈A邪 ? A rethorical question : would you have A ? Can it be possible that you have A ?
何 how
得車之多也？the use of 之 adds some emphasis : how could you obtain so many chariots ?
行 to go
矣 indicates a change, here is used for imperative
子行矣！Off with you !