What does ERROR 500 mean?

What does ERROR 500 mean?

I am not a computer whizz. I look after a local community centre website. updating it with events, news, etc.and was happy with the old panel and website builder I used to access and update the site.
In response to email about moving to the new control panel I looked at the instructions and opted to pay for hostinger to host the site and make the change over. They tried but the site is encoded so they couldn’t host it and I have moved back to 000webhost, on the new control panel

But now when I try to log in to the website builder I get ERROR 500.

How do I regain access to update the website?

@kateg visit /wp-content/plugins and delete the one completely that you installed to cause the error; also within public_html delete the .htaccess file via file manager/FTP also.
See if this solves your issue.

Also check this tutorial