This is the 532nd most frequent Japanese word.
以前
"以前" means "before" or "previously."
In this sentence, '以前' indicates a time in the past when the subject 'he' lived in this town. It is used to refer to past experiences.
彼は以前この町に住んでいた。
He used to live in this town.
Here, '以前' is used to denote a time period preceding the current conversation context, representing something that happened 'before' when specified.
以前から彼女のことを知っていました。
I have known her since before.
In this case, '以前' is applied to describe 'prior experience,' referring to experience gained at an earlier time, relating it to its potential usage.