This is the 11652nd most frequent Portuguese word.
perna
Leg.
In this sentence, 'perna' refers to the anatomical part of the body, specifically the leg.
Eu machuquei a minha perna enquanto jogava futebol.
I hurt my leg while playing soccer.
Here, 'perna' metaphorically describes the supporting structure of the table, commonly referred to as a 'leg' in English as well.
Minha mesa tem uma perna quebrada.
My table has a broken leg.
In this sentence, 'pernas' refers to the limbs of the dog used for running.