In Hesiod’s story, Hermes gave Pandora her name after the other gods supplied her gifts.
Works and Days describes Zeus ordering the creation of a woman who would bring trouble to humanity. Hephaestus shapes her, while other gods provide qualities and adornments. Hermes then gives her a voice and names her Pandora, linking her identity to the gifts contributed by the gods.
Hermes is the messenger of the gods and is also associated with language, persuasion, travel, and exchange. His role in the Pandora episode fits the story’s emphasis on communication and presentation, although the exact details vary across translations of Hesiod’s Greek.
This question is distinct from the later attribution of particular qualities. Hesiod’s account assigns many contributions to different gods, while Hermes’s specific role here is naming Pandora and giving her speech. Hephaestus is the divine craftsman who fashions her, so the two gods are sometimes confused in simplified retellings.