it maybe grandmother or grand father
There is no relation between you and your grandmother's cousin-in-law's grandson.
Your grandmother's brother is your parent's uncle. The uncle's child would be your parents first cousin. You would be second cousins.
Your sister's son is her grandson and your great nephew. Some use the term "grand nephew."
Your father's first cousin's grandchild is your second cousin, once removed. Your father's second cousin's grandchild is your third cousin, once removed. Your father's third cousin's grandchild is your fourth cousin, once removed. And so forth.
Your cousin's cousin could either be your cousin or no relation at all.
He is of relation as a cousin-in-law.
1st cousin 2x removed
Well, your cousin's brother is also your cousin, and a cousin's son is also your cousin.
Your cousin. You are that person's second cousin.
They are your cousin-in-law.
Second cousin
Cousin in Law