What is free choice?

Hello Rabbi,
I assume you've already dug into this a lot, so sorry, but I have a question that's been bothering me for a long time regarding free choice, and although I've read many of your articles, I haven't been able to find a clear answer to it (maybe I didn't search deep enough).
What exactly is free choice? If I understand correctly, free will is defined as something that appears without a prior cause. The question is where it appears, and especially who causes it to appear (apparently the answer is no one). If there is someone who causes it to appear, then it is causality, and if there is no one who causes it to appear, why is it considered that the person is the one who chose, if the desire appeared in his heart out of nowhere? If that is not randomness, I do not understand what is, and how can a person be punished later for a choice that he did not make.
If I understand correctly, the rabbi is not claiming that this is how free choice works, but rather through "discretion," which is a vague concept that I don't understand what he really means. If it's a certain calculation of the values ​​and advantages and disadvantages of each option, then I don't understand what I'm not explaining here. If not, then again, what is it?
If the answer is that free choice is something that we don't fully understand how it works, I don't understand why it's impossible to claim that God knows the future even though we have the ability to choose. After all, we don't understand what free choice is anyway, so we may not understand how He knows the future.
Thank you in advance.