Your sister's daughter is your niece, and her son is your grand nephew (or great nephew). You are his great uncle (if you are a man) or great aunt (if you are a woman).
Grand-Nephew
Your sister's son is your nephew His sons are your grandnephews, and his daughters are your grandnieces.
your second nephew
Charles Drew had 3 sisters, a wife, 3 daughters, and a son.
Daughters of one (or both) the same parents are either sisters or half sisters.
Charles Drew had 3 sisters, a wife, 3 daughters, and a son.
Your sister's son is your nephew His sons are your grandnephews, and his daughters are your grandnieces.
They are second cousins
Charles Drew had 3 sisters, a brother, a wife, 3 daughters, and a son.
Charles Drew had 3 sisters, a brother, a wife, 3 daughters, and a son.
No, because my father's sister (my aunt) does not have any sons, she only had daughters.
Some nieces of sisters are related to each other and some are not. Your niece is the daughter of your brother or sister (your siblings). If you have more than two siblings and at least two of them have daughters, those daughters are your nieces and they are first cousins to each other. You can also have a niece who is the daughter of a sibling of your spouse. If two sisters have nieces who are daughters of their spouse's siblings, those nieces are not related to each other (unless the spouses are related to each other, as when two brothers marry two sisters)