Not really sure, but it appears to relate to accessibility so I would leave it alone. It has a hidden attribute so it's probably not visible. To see what's getting inserted in that code you can go to your en.default.json file ctrl + f for "general" then look for the accessibility object inside the JSON structure.
This is an accepted solution.
"a11y" stands for "computer accessibility". In this case, consider if a someone with some sort of blindness uses your site and (they correctly set up their accessibility settings on their device), these lines of code will tell the user's device to play audio telling them how to interact with your site as well as giving feedback as they interact.
So my guess is the first line gives the message when the page is refreshed, the next line gives a message when an item is selected(or maybe how to select), and the third line gives slideshow instructions.
Having an accessible site not only allows more potential customers to use your site, it also helps with SEO. I hope this helps.