Your daughter and your first cousin's son are second cousins to each other.
Your uncle's sons and daughters are your first cousins.
Your first cousin is your son's first cousin once removed.
They share a common Grandparent. That makes them first cousins.
Your mom and her uncle's son are cousins, of the same generation, first cousins. Your mom's uncle's son is your first cousin, once removed (by one generation). If he has children, they will be your second cousins. (Children of first cousins are second cousins to each other.)
Your son and your nephew are first cousins to each other. Their daughters are second cousins to each other.
Your son and your niece are first cousins to each other. Your son and your niece's son are first cousins, once removed.
Cousine
You and your first cousin's son are first cousins, once removed.
Your cousins son will be your second cousin xx
Your son and your niece are first cousins. Her daughter and your son are first cousins, once removed.
third cousin once removed
Your daughter and your first cousin's son are second cousins to each other.