A junta is defined as a small group that controls the government.
It is usually a group of members of the military (but sometimes the political class too) which takes over control of the government by force. Very often, a junta is in power after a revolution.
For example, the Junta Militar de Gobierno (1973-90) was the military dictatorship which replaced President Salvador Allende of Chile after he was overthrown by a coup d'état in 1973.
