en_tn_condensed/gen/15/16.md

In the fourth generation

Here one generation refers to a lifespan of 100 years. "After four hundred years"

they will come here again

"your descendants will come back here." Abraham's descendants would come to the land where Abram was then living, the land that Yahweh had promised to give to him.

has not yet reached its limit

"is not yet complete" or "will get much worse before I punish them"