The word translated in the CEV as "common sense" is דַּ֫עַת (daʿat), a common word meaning "knowledge". The semantic range is quite broad: from visual and auditory perception, to matters of technical skill, to emotional/sexual knowledge, to knowledge of the divine. The word is frequently used in parallel with ḥoḵmâ ("wisdom"), particularly in Proverbs.
The reason behind CEV's choice of "common sense" is not perfectly clear to me. The verse is more formally translated by the ESV:
כִּֽי־יְ֭הוָה יִתֵּ֣ן חָכְמָ֑ה
For the LORD gives wisdom;
מִפִּ֗יו דַּ֣עַת וּתְבוּנָֽה
from his mouth come knowledge and understanding...
V. 2:6b thus restates, or perhaps expands, 2:6a. The semicolon works nicely here in English. CEV appears to me to shirk from what may be perceived as redundancy:
All wisdom comes from the Lord,
and so do common sense
Indeed, the translator's discomfort with synonymous parallelism is a consistent pattern in vv. 1-6. Presumably this was thought to be inconsistent with the CEV's stated aims
The translators of the CEV followed three principles; that the CEV:
- must be understood by people without stumbling in speech
- must be understood by those with little or no comprehension of "Bible" language
- must be understood by all.
After smoothing out the "doubling" structure of the verse and dispensing with "from his mouth" (a literal rendering, and admittedly a bit obscure), one is left with the list of items that come from the LORD: wisdom, knowledge, and understanding. The translator apparently felt that good, simple English did not allow for such apparently needless overlap (on which, see von Rad, below), so he elected for "common sense" to add some variety.
Interestingly, v. 6 contains the third use of the term "common sense" in CEV translation of Proverbs 2. Both of the earlier two translate a different Hebrew word: תְּבוּנָה (tĕbûnâ, "understanding"). This also appears to be an attempt to circumvent its juxtaposition with the nearly indistinguishable בִּינָה (bı̂nā).
von Rad's description of the literary devices at work in the Hebrew here is worth reading, and, I think, explains the unease that prompted the CEV's decision to stray from precise translation of the Hebrew in these verses. He describes the "playful coordination" of the various wisdom words:
Not infrequently, in parallelism, they become intertwined almost to the point of a synonymity which is often difficult for us to understand. Naturally these words are not, strictly speaking, synonymous, but the teachers believe that there is no better way of presenting their subject-matter in appropriate fashion, not by the use of terms which are clearly differentiated one from the other, but by the opposite means, namely by the juxtaposition of words related in meaning...
He goes on to point out the "ceremonial quality in the speech.... a circumstantiality in the speech which has become a game." This is a feature of the wisdom of Proverbs which may be comprised in translation according to the CEV's stated goal of being "understood by all.... without stumbling."