A Unary Operator is an Operation with only one Operand, i.e. a single input.
The exclamation mark ! means no, i.e. defines a Negation of a boolean type.
Plus + and minus - can be applied to some numeric values that will be interpreted as positive or as negative sign.
One can ask if a Variable is BOUND and the result will be a boolean, it is either bound which means it has a Value, i.e. the result is True, or it has not a Value, than the result is Zero or False. One can ask if an RDF term A is an URI or not and the result will be boolean True or False. Then one can ask if a RDF term is a Blank Term, if it is a Literal or if it is a string. One can also ask for a Language tag, i.e. which Language does a specific String or Literal has. Finally it is possible to ask for a DATATYPE that means which Datatype has a specific given Literal and the Datatype will be given back as the URI of the according Datatype.