The literal meaning is someone who has been physically restrained, usually by law enforcement. The connotative meaning is someone who is in a situation where there are no options.
'Being' has two distinct senses: 1: the state or fact of existing; 2: a living thing that has (or can develop) the ability to act or function independentlySource: True Knowledge
"Being Frank" has two meanings. The first is obvious. Being someone named Frank. The second which is the one you were probably thinking about when you asked this question means getting to the point...