wiederholen
to repeat
To say, write, or do something again. This verb is not separable.
Könnten Sie die Frage bitte wiederholen? Ich habe sie nicht verstanden.
Could you please repeat the question? I didn't understand it.

to repeat / retrieve
Loading your saved state.
to repeat
To say, write, or do something again. This verb is not separable.
Könnten Sie die Frage bitte wiederholen? Ich habe sie nicht verstanden.
Could you please repeat the question? I didn't understand it.

This word has two variants with different meanings and grammar. The inseparable verb 'wiederholen' (stress on '-ho-') means 'to do/say something again'. The separable verb 'wieder holen' (stress on 'wie-') means 'to fetch something back'.
Er wiederholt die Klasse. (untrennbar: Er macht die Klasse nochmal)
He is repeating the grade. (inseparable: He is doing the grade again)
In the meaning 'to say or do something again', 'wiederholen' (to repeat) is always inseparable. The prefix 'wieder-' stays firmly attached to the verb in all sentence forms.
Ich habe seinen Namen nicht wiederholt.
I did not repeat his name.
When an event or pattern occurs again by itself, the reflexive form 'sich wiederholen' (to repeat itself) is used. The subject is then the event itself.
Solche Fehler dürfen sich nicht wiederholen.
Such mistakes must not repeat themselves.
In the context of learning, 'wiederholen' (to review/repeat) is often combined with learning content. Typical objects are vocabulary, grammar, a chapter, or the course material.
Vor dem Test wiederhole ich immer alle wichtigen Vokabeln.
Before the test, I always review all the important vocabulary.
When 'wiederholen' means 'zurückholen' (to fetch back), it is separable. The particle 'wieder' stands at the end in a main clause. In the infinitive, it is written as one word: 'wiederzuholen' (to retrieve).
Er musste umkehren, um seine Jacke wiederzuholen.
He had to turn around to retrieve his jacket.
to learn
'lernen' and 'wiederholen' both belong to learning for school, university, or work. 'lernen' is used when you acquire new knowledge or a new skill. 'wiederholen' is used when you have already learned something and go through it again so that you remember it better. Learners may confuse the words because before an exam you often do both. Put simply: first you learn something, then you review it.

Im Büro wiederholt sie heute die wichtigsten Punkte für die Präsentation.
At the office today, she is reviewing the most important points for the presentation.
Zu Hause lernt das Kind, wie man die Uhr liest.
At home, the child is learning how to tell the time.