This is the 753rd most frequent Spanish word.
disponible
Available.
Here, 'disponible' means 'available' and describes the state of the book being obtainable at a future time.
El libro estará disponible en la biblioteca mañana.
The book will be available at the library tomorrow.
In this sentence, 'disponible' indicates the presence of free or unoccupied space.
Hay espacio disponible para estacionar tu auto en la calle.
There is available space to park your car on the street.
Here, 'disponible' is used to describe the constant accessibility of the customer service line.