die Ausgabe
expense
An amount of money paid for something. Usually used in the plural, 'Ausgaben' (expenses).
Der Kauf des neuen Computers war eine unerwartete Ausgabe.
The purchase of the new computer was an unexpected expense.

expense / issue / output
Loading your saved state.
expense
An amount of money paid for something. Usually used in the plural, 'Ausgaben' (expenses).
Der Kauf des neuen Computers war eine unerwartete Ausgabe.
The purchase of the new computer was an unexpected expense.

'Die Ausgabe' is the noun related to the verb 'ausgeben' (to spend / to hand out / to publish). The meanings of the noun (money, edition, distribution) are derived from the meanings of the verb: to spend money, distribute something, or publish something.
Wie viel Geld gibst du pro Monat für Lebensmittel aus?
How much money do you spend on groceries per month?
In the meaning 'Geldbetrag' (amount of money), the plural 'die Ausgaben' (expenses) is almost always used, often in contrast to 'die Einnahmen' (income/revenue). The singular 'eine Ausgabe' (an expense) is less common and refers to a single payment.
Wir müssen unsere monatlichen Ausgaben besser kontrollieren.
We need to control our monthly expenses better.
When a publication is meant, typical combinations are 'die aktuelle Ausgabe' (the current issue), 'die neueste Ausgabe' (the latest issue), or 'eine alte Ausgabe' (an old issue) of a newspaper or magazine.
Ich habe die letzte Ausgabe der Zeitschrift leider verpasst.
Unfortunately, I missed the last issue of the magazine.
'Ausgabe' can refer to the action of distributing or to the place. The preposition 'an' (at), e.g., 'an der Ausgabe' (at the distribution point), is a clear signal for the place, while the action is often described without a preposition or with 'von' (of).
Die Ausgabe der Getränke erfolgt nach dem Rennen.
The distribution of drinks takes place after the race.
In the meaning 'Output' (output), the word belongs to the technical language of computer science and technology. It describes data that a computer or device generates.
Der Sensor liefert eine digitale Ausgabe der Messwerte.
The sensor provides a digital output of the measured values.
book
'das Buch' and 'die Ausgabe' can both occur with printed or digital publications, but they do not mean the same thing. 'Buch' means the work or the readable object itself. 'Ausgabe' means a specific version of that book, for example a new, abridged, or specially designed edition. The words can be confused because you can buy, read, or find both in a library. In practical terms: the novel is the book; the hardcover, digital, or revised form can be a specific edition.

Für die Prüfung braucht die Klasse die neue Ausgabe des Lehrbuchs.
For the exam, the class needs the new edition of the textbook.
In der Bibliothek sucht Frau Kaya ein Buch für ihren Sohn.
At the library, Ms. Kaya is looking for a book for her son.