I am creating a website sitemap, someone suggested me to mind the hrefFlag. But i do not have idea about it.

Can someone describe the meaning of this and how should i utilize for my website?

It is only relevant if you have a multi language website. See this help page:

https://www.microsystools.com/products/sitemap-generator/help/website-page-url-language/

I think the HrefFlag tag can be implemented on any of domain. If you have multi-lingual sites means a site in different languages than you can use the HrefFlag tag on your site.

The hreflang attribute specifies the language of the linked document.

Basically this help you to make you multilingual websites

The hreflang attribute explain the language of the linked webpage.

Short for Hypertext reference, HREF is a pointer to another page. Following is an example of the A HREF HTML tag pointing to the Computer Hope page.

Hreflang attributes may not enable you to expand traffic; rather, the objective of utilizing them is to serve the correct substance to the correct clients. They help web crawlers swap the right form of the page into the SERP based on a user's area and language preferences. It is a good technique to use the Hreflang tag in the sitemap.

HTML links are defined with the <a> tag. The link address is specified in the href attribute.
If you have multi-lingual sites means a site in different languages than you can use hreflang tag on your site.