Meaning of this annotation ???

I am working on Smart Fields on OData .

I am trying to figure the meaning of the all the annotations .I am using the this blog .

But when I am using the vocabularies in SAP OData , I see another annotation ."Label" (not mentioned in the blog)

I was looking at the SAP UI5 library sample page link .I am not able to understand what does this annotation "Label" do .