Hermes gave Pandora the ability to speak in Hesiod’s account of her creation.
Pandora is assembled through contributions from several gods. Hephaestus fashions her body from earth, Athena gives her skills associated with crafts, and Aphrodite supplies beauty and desire. Hermes contributes a deceptive or shameless character and, in common summaries of the passage, gives her speech.
The story is not simply a catalogue of gifts that make Pandora attractive. Hesiod presents the gods’ contributions as part of Zeus’s plan to create a “beautiful evil” for humanity. Pandora’s appearance and abilities therefore serve a divine punishment rather than an ordinary human birth.
Hermes is often recognized as the messenger god, but his mythological roles also include cunning, persuasion, trade, and boundary-crossing. Those qualities make his association with Pandora’s speech especially relevant. Different translations phrase the exact attributes differently, so “speech” is the concise answer to the traditional identification.