In order to determine the intent of a possibly friendly or neutral monster or to pass along your intentions or desires,
some form of communication is necessary.
Speech might do for human-types, as the common tongue is known by most.
But what of an encounter with a giant, blink dogs, or dozens of similar creatures?
An open and raised right hand is possible,
and simply refraining from hostile moves will possibly allow for further exchange.
Remember though, that you cannot bribe a band of ogres to allow you to pass through unless you con communicate clearly.
 

see Negotiation +