How can we use <metadata>??? And UTF-8

Answer 1

check this for full information about meta tag:
https://www.w3schools.com/tags/tag_meta.asp

<meta charset="UTF-8">

Answer 2

Meta tags are snippets of text that describe a page's content; the meta tags don't appear on the page itself, but only in the page's source code. Meta tags are essentially little content descriptors that help tell search engines what a web page is about.

source: wordstream