Upfront admission: I'm just a novice at Spanish like you, so don't take my answer as any authority whatsoever...
But I did often see "you" translated two different ways in sentences when practicing cards in Anki as well... and it certainly confused me too. Such as ...
¿Estás listo para pedir?
¿Está listo para pedir?
As far as I've come to understand it, the primary difference stems from formality. The first form, estás, is the friendly\casual version of you, the second form, está, is the respectful version of you. You'd use the respectful form in specific social situations, such as if you're a child, if you're in a position of submission, or if in formal settings. So maybe consider it a bit like how we are comfortable using certain voices, contractions, phrases only in certain situations in English.
As Emily noted, están would indeed be to a group of people. However I'm pretty sure you still use it to mean a subject of what we might colloquially say in English as you all. It definitely works in polite settings, such as when addressing a gathering with ¿como están?.
Then, as Carlos noted, the vosotros form (estáis), where used (mainly in Spain and parts of South America?) comes in when less formal.
I believe (and please someone correct me if I'm wrong!) that estáis is mostly the informal version of you all.
Such that the real direct comparisons informal to formal comparisons are:
estás -> está (single person)
estáis -> están (multiple people)
In those places where vosotros is used.
But I did come into this question thinking that in vosotros-less places, estás could work for a less formal version of you all, but it appears I've learned something from the other answers!
Regardless, it boils down a lot to formality\politeness regardless.
Suffice to say, I sure find learning Spanish pretty complex too. It probably has a bit more complicated regional variability than English has. But it also is a bit more consistent and reliable at some things (pronunciation\spelling, grammar).
But slowly but surely it does get better, through all the mistakes and errors. Persistence friend!