How do you say these two sentences in BANGLA...??

'' This is my smaller cousin, Sandra, who is six years old. ''

'' And this is my other small cousin, Karolina, who is 9 years old ''

pls spell out the numbers.

"6" is "chhoy" (rhymes with "boy", and nine is "noy" (also rhymes with boy).

Cousin has so many different versions... Indian versions differ from Bangaldeshi versions. Here are the Bangladeshi versions of cousin:

mamato bone: mother's brother's daughter
chachato bone: father's brother's daughter
phupato bone: father's sister's daughter
khalato bone: Mother's sister's daughter

mamato bhai: mother's brother's son
chachato bhai: father's brother's son
phupato bhai: father's sister's son
khalato bhai: Mother's sister's son

You can just use "bone" or "bhai" which mean sister and brother, but also girl cousins and boy cousins. You can in fact use the word cousin too, almost everyone knows what cousin means.

So, to answer your question:

'' This is my smaller cousin, Sandra, who is six years old.''
>>> Eyta amaar chhoto (mamato/ phupato/ khalato/ chachato) bone (or cousin) Sandra. Or boysh chhoy bochhor.

'' And this is my other small cousin, Karolina, who is 9 years old ''
>>> Ar eyta amaar arek chhoto bone Karolina, noy bochhor.

1st ans-"eyta amar shob theke choto pistoto bon,sandra,or chaw bochor boyesh"
2nd ans-"eyta amar choto bon,karolina,or naw bochor boyesh"

There is no cousin in exact terms in Hindi and Bengali/ Bangla.

This is Sandra: Eta aamar Bone , Sandra.
Bon = sis.

She is 6 yrs old= Or boyesh, chha bochhar.

6= chha
bochhar= years

My sis = "Aamar Bone"

"Aar eta holo Karolina; Or boyesh nau Botcher."

Boyesh = age.
Cousin can be :
1. Khurtuto Bone = Father's Brother's children

2. Pistuto Bone = Father's sis's daughters

3. Mamato Bone= Mom's brother's daughters.

Will stop here. It is all very complicated.
Hope this helps.