This is the 12683rd most frequent Spanish word.
nesta
"Nesta" is not a standard Spanish word; it might be a regional term or a typo.
Here, 'nesta' is a contraction of 'em' (in/on/at) and 'esta' (this), referring to the specific morning mentioned.
Ela está feliz nesta manhã calma.
She is happy this calm morning.
In this sentence, 'nesta' is the feminine form agreeing with 'livro', serving as a preposition indicating location, combined with 'esta' (this) for specificity.
Neste livro, há muitas informações úteis.
In this book, there are many useful pieces of information.
Here, 'nesta' connects the preposition 'em' (in) with 'esta' (this), indicating the specific house where the action will happen.