Browser Caching with Nginx's issue

Hallo,

i have use this tutorial but i have the problem. I put html files on epoch but these files are cached.

Clould anyone help me out please?

https://i.imgur.com/UlM31tr.png

atm i have add this code to resolve the problem, but im still confused why i need this

        add_header Last-Modified $date_gmt;
        add_header Cache-Control 'no-store, no-cache, must-revalidate, proxy-revalidate, max-age=0';
        if_modified_since off;
        expires off;
        etag off;