This is the 8535th most frequent Dutch word.
hetgeen
"That which" or "what".
Here, 'hetgeen' translates to 'what', specifying the direct object of 'zei' (said).
Ik begreep niet hetgeen hij zei.
I did not understand what he said.
In this sentence, 'hetgeen' defines the subject of the subsequent clause, referring to 'what' as the content of the experience.
Hetgeen we zagen, was adembenemend.
What we saw was breathtaking.
Here, 'hetgeen' functions as the direct object within the dependent clause, indicating 'what' in terms of subject implication.