In Spanish the translation of that phrase may vary according to the situation in which is used. Here are some samples:
1- Encantado de conocerte. Candid way. To a male or a female.
Situation: You say it to your friend's brother or sister.
2- Encantado de conocerle. Formal way. To one person (male or female).
Situaion: You say it to your friend's father or mother.
3- Encantado de conocerla. Candid way. To a female.
Situation: You say it to your friend's mother.
4- Encantado de conocerlo. Formal way. To a male.
Situation: You say it to yor friend's father.
5- Encantado de conocerles. Formal way. To males, females, or both simultaneously.
Situation: You say it to your friend's parents.
6- Encantado de conocerlos. Candid way. To males.
Situation: You say it to your friend's father and brother.
7- Encantado de conocerlas. Candid way. To females.
Situation: You say it to your friend's mother and sister.