What is paper space and how does AutoMEP use it?

Paper space (also called layout tabs) is where drawing sheets, title blocks and viewports live in AutoCAD. AutoMEP can put new work on a sheet instead of in the model: name the layout, for example 'add the general notes to the E-101 layout', or say 'on the sheet' to use the first one. That keeps border lines and sheet notes on the sheet, apart from the model geometry, and new sheets can carry your own title block. See "Can AutoMEP use my own title block on the sheets it makes?" for how to set that up.