Need help with a hacked site

I did have an issue earlier in the week however that was resolved (or so I thought) so I’m starting a new thread.

I have been hacked and am unable to access my dashboard. The error message I’m seeing is this:

Fatal error: Call to undefined function _get_custom_object_labels() in /home/content/69/9451269/html/wp-includes/taxonomy.php on line 500

can any one shed any light on what it might refer to? Something similar happened once before and I believe it was a rogue plug in which once deleted fixed the problem but I have no idea with this one.

I’ve read – https://codex.www.ads-software.com/FAQ_My_site_was_hacked – and most of it refers to those who can access their dashboard and what doesn’t is over my head.