A11y is not easy to understand, as it is full of high level definition. My tip is try to put yourself into the shoes of the users, which means testing your UI as if you can't do the common way, like navigating between component without mouse or touch, trying to set your app brightness to 0 (complete dark) and use it as if you are blind. There are laws and requirements that you can check and follow, but in general, no laws can help unless you yourself experience it ;)