The 18-year-old signed an extension with Arsenal before leaving for Germany on a season long loan deal.
Nelson has been superb for the Bundlesliga side this season having scored five goals from 10 appearances, including an excellent curling strike in Saturday's 4-1 win over Bayer Leverkusen.
Emery said he was impressed with the Englishman but refused to comment on whether the club would recall Nelson.
"He can take responsibility, minutes and confidence in a team where he can play more," Emery told reporters.
"Then the objective with him is to come back with us and grow with this experience. My experience in Spain and France is that with this loan the player can achieve this.
"With Reiss, we are very happy with him at the moment. We follow him every match. We are thinking about how he can help us in the future."
Asked if if there was any possibility of Nelson being recalled to north London: "At the moment we don't speak about that."