This is the 15200th most frequent Turkish word.
sopa
Stick; club.
The word 'sopa' here is used to mean a physical stick or rod, often used as a tool or for pointing.
Adam elindeki sopa ile ağacı işaret etti.
The man pointed to the tree with the stick in his hand.
Here 'sopa yemek' represents a figurative meaning, implying receiving punishment, often corporal punishment in a traditional sense.
Sopa yemek istemiyorsan kurallara uymalısın.
If you don't want to receive punishment, you must follow the rules.
In this sentence, 'sopa gibi' is used metaphorically to describe something as being thin or stick-like in appearance.