This is the 10668th most frequent Spanish word.
decena
A group or set of ten.
Here, 'decena' refers to a grouping of ten, which is a common way to quantify items typically bought in groups.
Compré una decena de huevos en el mercado.
I bought a dozen eggs at the market.
In this sentence, 'decena' is used to indicate a general quantity of ten individuals in a specific context.
La decena de amigos se reunió para la fiesta.
The group of ten friends gathered for the party.
Here, 'decena' denotes a set of ten items, often used in trade or sales contexts to refer to bulk purchasing.