What is wp-json?

Hello,

I am having load speed issues with wp-json. This piece of code takes more than 1 second to load, according to Pingdom website load speed test:

<https://mywebsite.com/wp-json/>; rel="https://api.w.org/", <https://mywebsite.com/>; rel=shortlink, <https://mywebsite.com/wp-json/>; rel="https://api.w.org/", <https://mywebsite.com/>; rel=shortlink

Does anybody knows what is this wp-json, what is it used for and how to remove it?

Any advice is welcome.

Rgs

IM