It is usual for the celebrant to give a brief explanation of what this ceremony means.
At a legal marriage ceremony, this is when the celebrant is required to let everyone know that she is authorised to perform the marriage and remind the couple of the legal definition of the marriage contract. Currently in Ausxtralia this means ‘the union of two people to the exclusion of all others to voluntarily entered into for life’
If you are having some other form of ceremony, Ishara will want to offer some explanation to the guests about what the commitment you are making means to you, ie. whether you consider this to be a binding life-long commitment, a renewal of an existing commitment (renewal of vows), or something else.