Your husband's sister is your sister-in-law. Her husband is your husband's brother-in-law. But your sister-in-law's husband is not related to you.
The children of your husband's siblings are your nieces or nephews. Their children are your great-nieces or great-nephews.
Your husband's sister's kids are referred to as your nieces and nephews by marriage. More specifically, you can call them your "nieces" if they are girls and "nephews" if they are boys.
you call her your daughter's husband's sister
sisters in law
She is your sister-in-law.
Brother-in-law.
Your sister-in-law.
your brother-in-law :)
You would call your husband's younger brother a brother-in-law.
Phillipp uncle
There is no specific word for the husband of your wife's sister. If you need a phrase, call him your "sister-in-law's husband."
either your niece's husband, or your nephew, or your nephew in law, etc