cousin!
You wold call them your brothers sons. Hope this helps :)
Your nephew?
That would be your Cousin.
errrr, no maybe nephew
Your father's brother's son is your first cousin and your daughter's second cousin.
The daughter of your brother is your niece.
That would depend on what my brother, if I had one, named his son. Provided he didn't name him something silly like Rainbow or Maynard. In which case, I would just call him Bubba. On a serious note, your brother's son would be your nephew.
my brother doesn't have a son.
your second cousin- in law or by her name lol
Your son would be the uncle of his brother's son.
the son would be the nephew