Seeing horns in a dream symbolizes strength and invincibility. It indicates that you will be able to defeat your enemies. If you dream of a ruler with two horns, it suggests that this ruler will gain power and establish control over those beneath them. This dream reflects your self-confidence and leadership abilities.
From Imam Muhammad Ibn Seerin's Dictionary of Dreams According to Islamic Inner Traditions â entry "Horn" (page 213).
In a dream, a horn means strength and invincibility. Having a horn in a dream means conquering one's enemy. If one sees a ruler having two horns in a dream, it means that such a ruler will control interests throughout the East and the West. A horn in a dream also represents a relative from whom one can draw benefits. If one grows two animal horns in a dream, it means that he will die from grief and coercion. A horn in a dream also represents a century, years, weapons, money, children, or the reason behind one's pride or his distinguished look. (Also see Trumpet)
Note: Islamic dream interpretation depends on the dreamer's circumstances and state. This is a general guide drawn directly from the source book.