What is an unsafe height of a wave?

Excuse me, but I'm curious about the topic of wave safety. Can you clarify for me what exactly constitutes an 'unsafe height' of a wave? Is it a specific measurement, like a certain number of feet or meters? Or does it depend on other factors, like the location, the strength of the currents, or the skill level of the surfers? Understanding the risks associated with different wave heights is crucial for ensuring the safety of both beginners and experienced surfers alike.