An embargo is an order stopping the movement of trade ships into or out of a country. If you can’t get those yummy Swedish fish, perhaps there has been an embargo on trade with Sweden!
The fact that ships cannot move during an embargo makes sense from the Latin root of the word, a verb meaning impede with barriers. If one government places a trade embargo on another, it can be an act of war between the two countries. But if an arms embargo is in place, many countries refuse to sell arms to a particular country because it is especially violent. As a verb, the use of embargo is a little broader. If you write an impassioned plea for peace, but the government embargoes it, no one will read your writing.