Haldir believes you are an enemy of the Orcs and goblins, and wants you to help defend the bounds of the Golden Wood while Galadriel is sent word of your need.
'I have sent word to Lady Galadriel, ${PLAYER}. She will weigh your need and determine what role the Elves will play in these new deeds in Moria.
'In the meantime, I would appreciate your help in patrolling the boundaries of the wood. Speak to my brothers Rúmil and Orophin and offer them your aid; they speak little of the Common Tongue, but hatred of the Orcs will be understood by all enemies of the one Enemy.
'You will find them on the far shores of Nimrodel, to the north. If you walk along the northern banks of the river, you will find my brothers.'
Rúmil and Orophin are stationed along the boundaries of Lothlórien. Haldir told you to walk along the north bank of the river Nimrodel to find his brothers.
Haldir has asked you to lend your aid to Rúmil and Orophin. They do not speak much of the Common Tongue, so if you cannot speak to them in Elvish, your mutual hatred of the Orcs must transcend the need for words.
Haldir is at his camp on the boundary of Lothlórien.
You have spoken with his brothers and repelled an attack by the Orcs, and should return now to Haldir.