It’s essentially a dog bearing its teeth and growling. Also, depends on the context. For example, sometimes a show of force is nothing more than words, “We know what you’re thinking about doing, and if you do it, no option is off the table.” That might make someone think twice about, say, invading an ally of a more powerful country. Or you send a carrier group through the South China Sea to send the message “We go where we want, and so can anyone, in international waters. You can’t just start building islands of sand and claiming to own the surrounding ocean. Try us.” That seems to be working less and less though.