"You love her."
Translation:Du elsker henne.
'du' is for the subject of a sentence, 'deg' is for the object of a sentence. In English we use the word 'you' in both cases. In Norwegian they differentiate it the same way English differentiates 'I' (subject) and 'me' (object).
'I love you' = 'Jeg elsker deg'
'You love me' = 'Du elsker meg'
The plural form of 'you' ('dere') is the same in both the subject and object of a sentence, just like in English.
'I love you (all)' = 'Jeg elsker dere'
'You (all) love me' = 'Dere elsker meg'