What's Assembly in Activator.CreateInstance("Assembly", ClassName)?

Sorry if this is a very stupid question, but I'm lost ... I have a solution called GPSd. This solution has 3 projects:

-GPSd.BData.DAO

-GPSd.Web.Entities

-GPSd.Testes

Since the latter (GPSd.Testes) is the StartUp project.

I'm trying to call the following line from within Entities:

var Dao = Activator.CreateInstance(null, NomeClasseDAO);

But I get an error message: Additional information: Could not load the HoldingGrupoDao type from the GPSd.Web.Entities assembly, Version = 1.0.0.0, Culture = neutral, PublicKeyToken = null.

What would this "Assembly" ????

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