While I'm studying German vocabulary from a dictionary, I constantly see that the definitions of verbs have abbreviations next to them, such as "jdm: jemandem" and "jdn: jemanden" and "etw: etwas". I learned the words, but I still do not know their significance in a dictionary. For instance, what is the difference between "jdm" and "jdn"?
My best guess is that they indicate the case of the object, like accusative or dative. But dictionaries don't provide the exact meaning, so I couldn't be sure. Even if that is the case, how can we understand the cases of verbs having just "etw" ? And if I'm wrong, how can we understand the cases of verbs anyway?