TL;DR Passive speaker
You've probably seen something like this before,
+-----------------+-----------+------------+
| LANGUAGE SKILLS | RECEPTIVE | PRODUCTIVE |
+-----------------+-----------+------------+
| | | |
| Auditory | Listening | Speaking |
| | | |
| Textual | Reading | Writing |
+-----------------+-----------+------------+
representing the four major areas of language learning (listening, speaking, reading, writing) and how they relate to each other. Receptive (more passive) skills are those involving language experienced (by the learner), and productive (more active) skills are those involving language expressed (by others).
Receptive skill proficiency naturally precedes productive skill proficiency because
- Well, the only way to learn new words is through a receptive method (unless you're making up words), so since they enter the vocabulary through a receptive method, it makes sense that comprehension would naturally be strongest there.
- When reading or listening, words are almost always in a specific context, and meaning can be much easier derived from it, as opposed to when attempting to recall a word, when context (aside from experience with the word) is not available.
Proficiency in receptive areas can be called receptive (language) competency or passive knowledge, and those exhibiting this characteristic are called passive speakers:
A passive speaker (also referred to as a receptive bilingual or passive bilingual) is someone who has had enough exposure to a language in childhood to have a native-like comprehension of it, but has little or no active command of it.
Note: The term "passive speaker" also includes reading comprehension.
Here's another useful link on passive vs active vocabulary.