1Usual, ordinary, everyday — the normal, non-special state of things or a habitual way of being. Used as a noun or with の as a modifier (普段の生活, 普段着). The kanji are ateji; the word was originally written 不断.
旅行から帰って、普段の生活に戻った。
After coming back from the trip, I returned to my usual life.
普段着のままで来てください。
Please come in your everyday clothes.
普段の彼からは想像できない行動だった。
It was behavior I couldn't imagine from the usual him.
普段の努力が試験の結果に表れる。
Your everyday efforts show up in your exam results.
2Used adverbially to mean 'usually, normally, on a regular basis.' Most often appears as 普段は or 普段から, describing habitual or regular states and actions.
私は普段、朝ごはんを食べない。
I usually don't eat breakfast.
普段は電車だが、今日は車で来た。
I normally take the train, but today I came by car.
彼は普段からよく本を読んでいる。
He regularly reads books.
普段あまり料理しない父が、今日は夕食を作ってくれた。
My father, who doesn't usually cook, made dinner for us today.