der Ausflug
excursion
A short trip or outing, usually taken for pleasure and often lasting only one day.
Am Wochenende machen wir einen Ausflug an den See.
At the weekend, we're taking an excursion to the lake.

excursion / digression
Loading your saved state.
excursion
A short trip or outing, usually taken for pleasure and often lasting only one day.
Am Wochenende machen wir einen Ausflug an den See.
At the weekend, we're taking an excursion to the lake.

The word 'Ausflug' (excursion/digression) is composed of 'aus' (out) and 'Flug' (flight). Figuratively, it describes that you 'fly out' of everyday life for a short time in order to experience something pleasant.
Für Sonntag ist ein Ausflug in die Berge geplant.
An excursion to the mountains is planned for Sunday.
An 'Ausflug' (excursion) is typically 'gemacht' (made/done). So you say 'einen Ausflug machen' (to take an excursion). The destination is often indicated with prepositions such as 'an', 'in', or 'zu'.
Lass uns am Samstag einen Ausflug an den Badesee machen.
Let's take an excursion to the swimming lake on Saturday.
You can recognize this figurative meaning by the fact that it is not about a place, but about a topic. Signal words include 'Geschichte' (history), 'Philosophie' (philosophy), or 'Thema' (topic).
Der Professor machte einen kurzen Ausflug in die römische Geschichte.
The professor made a brief digression into Roman history.
The meaning 'Abschweifung' (digression) is mainly used in written language, in lectures, or in formal discussions. In normal everyday conversation, it is rather rare.
Bevor wir zum Hauptpunkt kommen, gestatten Sie mir einen kleinen Ausflug in die Statistik.
Before we come to the main point, allow me a small digression into statistics.
journey / trip
'die Reise' and 'der Ausflug' can both mean that you travel or go to another place. 'Reise' is more general and often longer, for example several days or to another country. 'Ausflug' is usually short, often just for one day, and is usually done for fun or relaxation. The words can be confusing because an 'Ausflug' can be a small 'Reise'. If you come back in the evening, 'Ausflug' often sounds more natural; for a greater distance or a longer period of time, 'Reise' fits better.

Nach dem Unterricht plant die Klasse einen Ausflug ins Museum.
After class, the class is planning an outing to the museum.
Unsere Reise nach Spanien dauert zehn Tage.
Our trip to Spain lasts ten days.