Here you are.

biometrics mean finger print plus photo and signiture.
( FP cide 2). All these are for your final making green card. Some time immigration ask us to do it together with first FP (code 1). So probably you heard of ***** did FP code 3 ( code 3 = code 1+ code 2). So for your case, if FP is code 3, they ask you to do all; but if you already did FP ( Code 1) before, they will ask you to capture your biometrics ( right index finger print + take digital photo + your signiture). That is all but not sure you get the point.