Everybody involved in software engineering knows that accessibility (or A11y) matters. And while we all agree that it's a good thing, we don't always prioritise it. I think we're long overdue in doing a better job. Or even better, consider it an intrinsic part of our basics.
A11y means the way that your product is, quite literally, accessible by any user. We can capture a11y in numbers, that beautifully translate into contrast ratios, tab orders, the amount of ARIA labels and whatnot. The most important thing to realise though is, that you should be aware that other users have other needs and maybe limitations that you should take into account.