Your niece and your daughter are first cousins.
Your daughter and the daughter of your niece are first Cousins, once removed.
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)
My niece's daughter is my great niece.
If you have two nieces who are not sisters but are each the daughters of your siblings, the two nieces are first cousins. If they each have a daughter, those daughters are second cousins to each other.
Your niece's daughter is your grand niece, or, as some would say, your great niece.
Your daughters are great aunties if their nieces have kids. Your daughters kids are your grand children.
The daughters of your sister are your nieces.
Your brother's daughters are your nieces
Your brother's daughters are your nieces
Your mother's sister-in-law is either the wife of her brother (your uncle), or your father's sister (your aunt). The niece of your uncle's wife is not related to you, unless she is you, your sister, or a girl cousin who is the daughter of another of your mother's brothers or sisters. The niece of your father's sister is you, your sister, or the daughter of another of your father's brother's or sisters. If your father's sister is married, she may have nieces who are the daughters of her husband's brothers or sisters. Those nieces are not related to you.
Grand niece.
Nieces are the daughters of your brothers and sisters. Nephews are the sons of your brothers and sisters.
I can give you several sentences.My nieces are coming for a visit.Are those girls your nieces?Nieces are the daughters of your brother or sister.