die Klippe
cliff
A steep, high rock that rises out of the sea or along a coast.
Wir standen oben auf der Klippe und blickten auf das tosende Meer.
We stood at the top of the cliff and looked out at the roaring sea.

cliff
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cliff
A steep, high rock that rises out of the sea or along a coast.
Wir standen oben auf der Klippe und blickten auf das tosende Meer.
We stood at the top of the cliff and looked out at the roaring sea.

You can recognize the figurative meaning by the fact that it is not about geography. When exams, negotiations, or projects are being discussed, 'Klippe' (cliff/obstacle) is a metaphor for a difficulty.
Die Gehaltsverhandlung war die letzte große Klippe vor der Vertragsunterzeichnung.
The salary negotiation was the last major obstacle before the contract was signed.
In the literal meaning, 'Klippe' (cliff) is often described with adjectives such as 'steil' (steep), 'hoch' (high), or 'schroff' (rugged). Typical verbs are 'stehen' (to stand), 'blicken' (to look), or 'klettern' (to climb).
Vorsichtig trat er an den Rand der steilen Klippe.
Carefully, he stepped to the edge of the steep cliff.
In the figurative sense, 'Klippe' (obstacle) is often used with the verb 'umschiffen' (to navigate around). 'Eine Klippe umschiffen' means to skillfully avoid or master a difficulty.
Dank guter Vorbereitung konnte er die schwierigsten Fragen im Interview umschiffen.
Thanks to good preparation, he was able to navigate around the most difficult questions in the interview.
danger
'die Gefahr' and 'die Klippe' can both refer to something difficult or risky. 'die Gefahr' is the general word for a situation in which harm can happen. In this relation, 'die Klippe' means a difficult point or an obstacle that has to be overcome. This is a figurative image. Literally, a Klippe is a steep rock or cliff, but here it is about a problem. If you are talking directly about risk, 'Gefahr' is more precise. If you want to describe a difficult obstacle figuratively, 'Klippe' fits.

Die wichtigste Klippe im Projekt ist der enge Zeitplan.
The most important obstacle in the project is the tight schedule.
Bei Glatteis besteht die Gefahr, dass jemand auf dem Weg zur Arbeit stürzt.
When there is black ice, there is a danger that someone will fall on the way to work.