HTML attribute hreflang is used to tell search engines which language and region are used on a specific developed page. It helps search engines to understand what version that user requires based on language and location region.
The Hreflang tag is mentioned in head section of country-specified pages and includes two letters one is language and other one is country code like en-us, en for English and us for united states.
link rel="alternate" href="https://www.myfreeonlinetools.com/" hreflang="en-us"
rel="alternate" Its specified tag used to tell search engines that it's an alternate version of an original web page, not the canonical page
href="link" It tells the search engine original URL of alternate page
hreflang="en-us" It tells to search engine language and country specified web page.