Hi Bibhash,
X and Pro supports up to 4 columns of products. This is common to other Wordpress themes as well because the space o the container of the products might be not enough to accommodate a lot of columns.
However, you can add some custom CSS in order to support 6 columns.
To do that, please add this in X > Theme Options > CSS:
.woocommerce .cols-6 li.product,
.woocommerce.columns-6 li.product {
width: 13.33333%;
}
@media (max-width: 480px) {
.woocommerce .cols-6 li.product,
.woocommerce.columns-6 li.product {
width: 100%;
}
}
Kindly note that since this is a custom code that changes the default behavior/display of the theme, you will be responsible to maintain or update the code in case you require further changes or if the code stops working in future updates. If you are uncertain how to proceed, it would be best to get in touch with a developer.
Hope this helps.