noun, used as a prefix
Used before era names or historical periods to mean 'pre-', e.g. 前近代 (premodern).
前近代の社会構造を研究している。
I am researching the social structure of premodern times.
noun, used as a suffix
Attaches after a noun to mean 'before' that event or point in time. Often used in formal or written contexts.
出発前にもう一度確認してください。
Please check once more before departure.
noun, adverb
Dated standalone noun/adverb meaning 'before' or 'earlier'. In modern Japanese, 前 (まえ) is far more common for this sense.
See also: 前 (まえ)
ぜんにも申した通り、この計画は中止です。
As I said before, this plan is cancelled.