It's a polite and common phrase used in greetings and introductions in these languages.
Here are some appropriate ways to respond to "encantado," depending on the context:
Formal:
* Igualmente. (Likewise.)
* El gusto es mío. (The pleasure is mine.)
* Mucho gusto. (Very pleased to meet you.)
Informal:
* Encantado/a también. (Delighted to meet you too.)
* Igual. (Same.)
* Un placer. (A pleasure.)
You can also add a personal touch to your response:
* "Encantado de conocerte." (Delighted to meet you.)
* "Me alegro mucho de conocerte." (I'm very happy to meet you.)
* "Es un placer para mí conocerte." (It's a pleasure for me to meet you.)
The best way to respond will depend on the formality of the situation and your relationship with the person.