This is most commonly used to attach an ontology (a set of tbox axioms in description logics jargon) to a reasoner. A certain amount of precomputation may be done at this time (e.g. constructing the class lattice). When the reasoner is later applied some instance data these cached precomputations may be reused.
In fact this call may be more general than the above description suggests. Firstly, a reasoner that supports arbitrary rules rather than ontologies may use the same method to bind the reasoner to the specific rule set (encoded in RDF). Secondly, even in the ontology case a given reasoner may not require a strict separation of tbox and abox - it may allow instance data in the tbox and terminology axioms in the abox.
A reasoner is free to simply note this set of RDF and merge with any future RDF rather than do processing at this time.
@param tbox the ontology axioms or rule set encoded in RDF
@return a reasoner instace which can be used to process a data graph
@throws ReasonerException if the reasoner cannot bebound to a rule set in this way, for example if the underlying engine can only accept a single rule set in this way and one rule set has already been bound in of if the ruleset is illformed.