This vision carries a very coherent biblical structure rather than symbolism. The elements relate to one another cleanly, which is usually a sign the vision is communicating a focused spiritual reality rather than random imagination...
This vision is an encouragement for a believer or believers (sheep) to remain at peace and to stand firm. The enemy (the goat) may puff himself up, make loud threats, and try to make you feel isolated or vulnerable and fearful. He may even taunt you during times of transition (the bridge). However, the Lord is showing you the spiritual reality behind the scenes: Your safety is hidden in Christ. "When the enemy comes in like a flood, the Lord raises a standard against him" (Isaiah 59:19). Do not entertain the enemy's arrogant words; his footing is far more unstable than he tries to make out.
“The Lord will fight for you, and you shall hold your peace.” (Exodus 14:14)