Your husband's sister is "la soeur de mon mari" in French, or "la belle-soeur" which is the term for the sister-in-law.
sister in law
Your sister's husband is your brother-in-law.
Your brother would call your husbands sister by her first name. Or, "my (sibling's) sister in law.
Your Sister-in-law
my sister is called Lisa > ma soeur s'appelleLisa.
"La soeur de ma mère" "Ma tante" : my aunt
you call her your daughter's husband's sister
There is no common ancestor, so you aren't really related. Related by marriage is one way to describe the relationship.
Mom
Ma soeur s'appelle________.
a sister is called 'une soeur' in French. 'soeur' is pronounced like 'coeur', that is about the sound of the English word 'Sir'
The French words for brother and sister are frere (brother) and seour (sister). There is a popular children's song which has "frere" in the title. It is called "Frere Jacques". This song is known in English as "Brother John".