Ok.
I would try to give a brief explanation.
Agglutination is the reaction that occurs between an antigen and its corresponding antibody to for clump(s). Such as antigen A and antibody A like i said earlier.

When a blood sample which contains antigen(with unknown antigen type) is mixed with an antiserum which contains the antibody (either A,Bor D), agglutination infere that the antigen is corresponding to the antiserum used.
So, if antiserum B is used and agglutination occur, it infere that the blood sample is grouped B.

And as for the rhesus factor (determined by the presence of antigen D in the blood), agglutination also indicate its presence i.e positive.

Any form of uniformity means negative since agglutination did not occur.

And also, the genotype is not same as the blood group.
The genotype is the genetic constition of an individual. Such as AA SS AC AS