The sermon delivered at an Eid prayer gathering is called a khutbah in Arabic.
Unlike the Friday khutbah, the Eid khutbah traditionally follows the two-unit Eid prayer rather than preceding it. The imam may address worshippers about gratitude, charity, community, moral conduct, and the religious meaning of Eid. The sermon is generally delivered while the congregation listens quietly.
The Eid prayer itself is known as Salat al-Eid and is performed in congregation on the mornings of Eid al-Fitr and Eid al-Adha. It includes additional takbirs whose exact number and placement vary among Islamic legal traditions.
Khutbah is a broad Arabic term, not a title used only for Eid. Friday prayers, the pilgrimage at Arafat, and other important religious occasions can also include a khutbah. The Eid khutbah should therefore not be confused with the adhan, which is the call to prayer, or with the prayer itself.