Agitation refers to the stirring, fiddling, and the disturbing of a brew in any way meant to help mix liquids and ingredients together.
It is often used in cafe terminology whereby coffee is agitated to mix coffee ground and to trigger more release of it’s flavor into the drink.
A lack of agitation is often the reason why certain beverages, especially coffee don’t taste the way it should.
Stirring sticks are often sufficient. But consumers are often given spoon to do their own agitation.