This is the 6546th most frequent Spanish word.
cana
Gray hair.
Here, 'cana' is used to denote a strand of grey or white hair, typically due to aging.
Encontré una cana en mi cabello esta mañana.
I found a grey hair in my hair this morning.
In this sentence, 'caña' refers to a type of tall grass used for producing sugar, specifically sugarcane.
En el campo cultivamos caña de azúcar.
In the countryside, we cultivate sugarcane.
Here, 'caña' is colloquially used in Spain to refer to a small draft beer, typically served in a glass.