tl;dr though this moron is misusing the term in trying to say that there are semantic differences between the interlocutors whenever he wants to reject an argument from definition. By saying that "you're stuck" epitomizing the hypothesis, he's making an incoherent claim to try to make it seem like the interlocutor is exhibiting some sort of defect, when in reality he's simply unwilling to evaluate definitions from a pragmatic basis. Instead, he is pretending that there is a more legitimate worldview corresponding to his view, yet he cannot articulate it without immediate rebuttal.
Why does he choose to use an esoteric artifact of linguistics and analytic philosophy instead of saying "irreconcilable semantic differences that shape our worldview"? Well, it's because that gives away that he's a coward and is yielding the conversation. Instead, he hopes to throw the reader off from the conversation hoping they don't know what he's talking about, while feigning some sort of intellectual ascendancy. In reality, he's just exposing himself as a doubly incompetent pseudointellectual bitxh (on top of being a genocidal Zionist). Feel free to use this hollow shell of a man as target practice.
So what is the Sapir-Whorf hypothesis? In short, it's a claim that languages (whether natural or artificial) affect the way that we think, since languages don't always map to each other. This incongruency between languages occurs both in the form of 1) syntax (meaning the form and structure of the language) and 2) semantics (meaning the words and meanings).
It had been noted that some natural languages are structured in closed logical form, which means in short that they map formal logic languages like propositional calculus or first order languages. Extrapolating from that, people could reasonably infer that some languages facilitate learning those formal structures, albeit not guaranteed that people will (see: Americans lmao).
Secondly, it has been noted that some languages have words that don't translate to words in other languages. Instead, at some point in history the practitioners of that language identified a concept and gave it a term, which makes that concept more readily available for use. Moreover, while words in different languages may refer to the same thing (the "rigid designator" lmao), how they conceptualize that thing per definition may vary. A famous thought experiment in philosophy involves a person pointing at a rabbit and calling it "Gavigai" and the observer being unsure as to what it means, as the definition could vary in many ways, for example: "a furry rodent with long ears" or "a collection and configuration of atoms that forms the image of a fluffy long eared animal when exposed to the visible light frequency". Whatever the exact conception it is, it is virtually inaccessible to the interpreter.
The whole Sapir Whorf hypothesis has been substantiated by philosophers and thinkers noting differences in the writing, methods, and argumentation style of scientists, where people note that German scientists are surprisingly strict and rigorous in their argumentation and methodologies, while French scientists tend to be a lot more loose and creative. This lead many to believe that it is language itself that has determined this difference. However, consensus amongst linguists and researchers is that it's not that simple.
Once again, feel free to enact violence against pseudointellectual fascists in Minecraft or whatever game you play.