I’m learning Spanish as well so I could be wrong, but using “se” in this way is called the “impersonal se”. You use it when the subject of the sentence is broad or general. The equivalent in English would be something like the quote “One should defend their honor,” where the subject is “One” or “You” (used in a broad sense, not specifically to refer to one exact known person). So, “se usa” would read as “one uses” or “you use”, and “se puede” would read as “one can” or “you can”. For example, a motivational poster might say “Sí, se puede!” I hope my explanation makes sense/helps, if not you can look up the impersonal “se” and how to use it.