voici ma sœur et son mari.
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.
Your sister's husband is your brother-in-law. The English language makes no distinction between the husband of an older sister and the husband of a younger sister.
how to say 1 sister in french is une soeur
"Sister" in French is "sœur."
To say "big sister" in French, you would say "grande sœur."
You can say "ma sœur" which means "my sister" in French.
You can say "ma soeur avait" in French to mean "my sister had."
Your father's sister is your aunt and her husband is your uncle. Some would say "uncle by marriage."
I help my sister is " j'aide ma soeur " in French.
You would say "petite sœur" in French to refer to a younger sister.
mari
Soeur.