Why it doesn't show??

Question

https://code.sololearn.com/WU42KNtUs3EO/?ref=app

Answer 1

https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Frame-Options

"The X-Frame-Options HTTP response header can be used to indicate whether or not a browser should be allowed to render a page in a <frame> , <iframe> or <object> . Sites can use this to avoid clickjacking attacks, by ensuring that their content is not embedded into other sites"

Answer 2

It's a security feature. Note that the use of frames is mostly outdated:
https://stackoverflow.com/questions/1203068/why-should-i-not-use-html-frames?utm_medium=organic&utm_source=google_rich_qa&utm_campaign=google_rich_qa