Here "horn" and "trumpet" mean the same thing. This command is given to the people of Gibeah and Ramah to emphasize that the enemy is coming. (See: [[rc://en/ta/man/jit/figs-doublet]])
Here "Benjamin" represents the soldiers from the tribe of Benjamin. This may be a request for them to lead the people into battle. But modern versions make various attempts to interpret this expression. (See: [[rc://en/ta/man/jit/figs-synecdoche]])
This was a city on the border between the northern kingdom of Israel and the tribe of Benjamin in the southern kingdom. See how you translated this in [Hosea 4:15](../04/15.md). (See: [[rc://en/ta/man/jit/translate-names]])