This is the 3016th most frequent Spanish word.
duero
Duero: A river in Spain and Portugal.
Here, 'Duero' is used as a proper noun to name a geographical feature, specifically a river.
El río Duero cruza España y Portugal.
The Duero River crosses Spain and Portugal.
In this sentence, 'duero' refers to the bottom or lower section of a cabinet, employing a less common usage of the word.
Guardé el libro en el duero del armario.
I stored the book in the cupboard's bottom.
Here, 'duero' is a misspelling or mispronunciation likely intended to mean 'debería' (should), illustrating the importance of accurate spelling in conveying correct meaning.