Brand new Jr. Sys Admin here, trying to wrap my head around the system in place. We've got a DB on Microsoft SQL Server 2008 and I want to get a visual on what tables & Fields are in place. Just so I can get a idea of what I'm dealing with in the ERP.
In SQL Server (or RDMBs for all pratical purposes) the schema is the object definition itself; the tables, columns, indexes, etc.
A visual representation of the schema, could be a UML (Unified Modeling Language) drawing or similar. In SQL Server these visual representations are called Database Diagrams.
You can create a new diagram using SSMS, in the Object Explorer, then you can add tables to your diagram.