Yahweh continued to speak to Abram while Abram dreamed.
I will judge
Here "judge" is a metonym for what will happen after God makes the judgment. AT: "I will punish" (See: rc://en/ta/man/translate/figs-metonymy)
that they will serve
The full meaning of this statement can be made explicit. AT: "that your descendants will serve" (See: rc://en/ta/man/translate/figs-explicit)
This is an idiom. AT: "many possessions" or "great wealth" (See: rc://en/ta/man/translate/figs-idiom)
you will go to your fathers
This is a polite way of saying "you will die." (See: rc://en/ta/man/translate/figs-euphemism)
The word "fathers" is a synecdoche for all ancestors. AT: "ancestors" or "ancestral fathers" (See: rc://en/ta/man/translate/figs-synecdoche)
you will be buried in a good old age
"you will be very old when you die and your family buries your body"
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"