Question

what is mean by chormosomes x,y

Answer 1

x and y are the sex chromosomes of a male

Answer 2

Hi !

In human beings there are 23 pairs of chromosomes ( 46 chromosomes in total)
Out of the 23 pairs, 22 pairs are called autosomes. The remaining one pair is called "sex chromosomes".
In male, the sex chromosomes are "X" and "Y"
In female, the sex chromosomes are both "X" and "X"

Hence, X and Y are the sex chromosomes ( of males)