#were pregnant by their father

"became pregnant by their father" or "conceived children with their father"

#He became

"He is"

#the Moabites of today

"the Moab people who are now living"

#of today

The word "today" refers to the time when the author of Genesis was living. The author was born and wrote this many years after Lot's family lived and died.

#Ben Ammi

This is a male name. (See: [[:en:ta:vol1:translate:translate_names]])

#the people of Ammon

"the descendants of Ammon" or "the Ammon people"