Architects communicate through drawings. We can draw the project at different scales showing, for example, how the building will look with-in the street (required for planning) down to the details of the size and shape of the skirting board. Every job is different and one or several drawings maybe required (all to be agreed with the client) 3d sketches can also be helpful and are available.  The drawings can act as a 'contract' on the job so that everyone involved, builder, structural engineer, QS (cost consultant) if applicable, knows what is involved and what is to be built.