At its simplest, a cursed corpse is a doll imbued with a jujutsu sorcerer's cursed energy. This cursed energy, depending on how it is used and the sorcerer's intent, allows the doll to come to life for a limited amount of time. The most basic of these cursed corpses follow relatively simple commands. For instance, one of Yaga's other dolls, Tsukamoto, is a small bear with boxing gloves that constantly sleeps as long as it has a constant flow of cursed energy poured into it. Disrupt that flow, and the bear will wake up and beat the tar out of whoever is holding it. Yaga uses Tsukamoto to teach students the basics of jujutsu, but it cannot be used for anything else.
However, Yaga isn't just some run-of-the-mill puppeteer. He's the foremost expert in the world on cursed corpses, and has made the only known cursed corpse that is ostensibly its own person. This "Abrupt-Mutated Cursed Corpse" is named Panda, and is actually one of the students at Tokyo Jujutsu High. By inserting three, instead of the normal one, jujutsu-imbued cores into Panda, Yaga is able to attune them so that Panda becomes something more than a mere doll. He has free will and can actually generate his own cursed energy, something that most cursed corpses eventually expend before dying.
