This is the 8399th most frequent Spanish word.
quart
"Quart" is not a Spanish word; it is an English word referring to a unit of liquid or dry capacity, equal to a quarter of a gallon. The Spanish equivalent might be "cuarto" (quarter) depending on context.
Here, 'quart' is used to indicate a measurement of liquid.
Compré un quart de leche ayer.
I bought a quart of milk yesterday.
In this sentence, 'quart' is demonstrated as part of a baking recipe, relating to an amount.
Debe añadir un quart de taza de azúcar a la mezcla.
You should add a quart of a cup of sugar to the mixture.
This usage describes the volume capacity of the object.