This is the 8759th most frequent Dutch word.
invallen
"Invallen" means "to fall in, collapse, step in, or interrupt," depending on the context.
Here, 'invallen' is used to mean 'occur to someone' or 'come to mind'.
Het idee begon mij ineens in te vallen.
The idea suddenly occurred to me.
In this sentence, 'invallen' implies 'streaming in,' as in light.
De zon begint in de kamer in te vallen.
The sunlight is beginning to stream into the room.
Here, 'invallen' is utilized to denote 'filling in' or 'substituting' for someone.