As a Noun:
1. A person whose job it is to listen or watch what someone is saying and translate it immediately into spoken or signed language. English = interpreter, sign language interpreter.
2. An explanation of what something means. English = interpretation.
As a Verb or Adjective:
1. To translate what someone is saying immediately into spoken or signed language. English = interpret.
1. This sign is a little old fashioned and is increasingly being replaced by the other sign for this meaning.