Good Evening
expression
This word is made of now and night with the hiragana は at the end. The は here is pronounced as わ (the old pronunciation). When you say "now night!" you're really saying good evening.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well. Just be aware that the は at the end is actually the particle は so it's pronounced like わ.
今晩は。こんな所で何してるの？
Good evening. What are you doing in a place like this?
「あら、今晩は。」「今晩は。」「昨日の社長とのミーティング、どうだった？」「それが....てっきりしょう進するものだと信じてたんですが、首になりました。」
"Oh hey, good evening." "Good evening." "How was the meeting with the president yesterday?" "Well, I was certain I would be promoted, but I was fired instead."
今晩は、コウイチおじさん。今日は私とフグの赤ちゃんの面倒をみてくれて有難うございます。あ、ところで、電子レンジは使わなかったよね？ 母乳だから、電子レンジ使ったらいけないんだよ。
Good evening, Uncle Koichi. Thank you for taking care of our baby today. Hey, you didn’t microwave that, did you? Because it’s breast milk, you’re not supposed to do that.