die Übung
practice
The repeated performance of an activity in order to learn, improve, or maintain a skill.
Durch tägliche Übung hat er sein Klavierspiel stark verbessert.
Through daily practice, he greatly improved his piano playing.

practice / exercise
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practice
The repeated performance of an activity in order to learn, improve, or maintain a skill.
Durch tägliche Übung hat er sein Klavierspiel stark verbessert.
Through daily practice, he greatly improved his piano playing.

The noun 'die Übung' is derived directly from the verb 'üben' (to practice). 'Üben' is the action of practicing, while 'die Übung' can refer both to the process and to a single task.
Ich muss für die Prüfung noch viel üben.
I still have to practice a lot for the exam.
You can recognize the exact meaning of 'Übung' from the context. 'Tägliche Übung' (daily practice) means regular training (m01). 'Eine Übung auf Seite 20' (an exercise on page 20) is a concrete task (m02). A 'militärische Übung' (military drill) is a maneuver (m03).
Mit etwas Übung wird es dir gelingen.
With a little practice, you will succeed.
In the meaning 'practice', 'Übung' is often used in fixed expressions. The proverb 'Übung macht den Meister' (practice makes perfect) is very well known.
Das Einparken braucht am Anfang etwas Übung.
Parking takes a bit of practice at first.
When 'Übung' means a task, it is often combined with verbs such as 'machen' (to do), 'lösen' (to solve), or 'bearbeiten' (to work on). Here, the plural 'die Übungen' is usually used.
Können Sie mir bei dieser Übung helfen?
Can you help me with this exercise?
The idiom 'aus der Übung sein' (to be out of practice) is a fixed construction. It is always formed with the verb 'sein' (to be) and describes that someone no longer masters a skill as well because of a lack of practice.
Ich habe seit Jahren kein Klavier mehr gespielt, ich bin völlig aus der Übung.
I haven't played the piano in years; I'm completely out of practice.
experience
'Erfahrung' and 'Übung' are closely connected because you get better through repeated action. 'Übung' means the training itself or a single task used for training. 'Erfahrung' is more what you have learned after many situations. You need 'Übung' to become more confident, and over time you gain 'Erfahrung'. Learners may confuse the words because both show that someone can do something better. If you mean active training, use 'Übung'. If you mean the knowledge gathered from practice, use 'Erfahrung'.

Nach ein paar Wochen Übung kann Sofia schon viel schneller tippen.
After a few weeks of practice, Sofia can already type much faster.
Adam hat durch viele Projekte Erfahrung im Planen gesammelt.
Adam has gained experience in planning through many projects.