Almost half of the new employees are already whining, even though it's been only a week since they joined the company.
new employees:新入社員
whine:めそめそ泣き言を言う(complain に似ていますが、情けない感じで不平をもらす、というニュアンスがあります。)
even though SV...:...なのに、...にもかかわらず
例)Even though we're the same age, you look much younger.(ぼくたち同い年なのに、君の方がずっと若々しいね。)
it's been only a week since they joined the company:会社に入ってからたったの一週間しか経過していない(it's been 〇〇 since ... は便利です。)
例)It's been ten years since we got married.(結婚してもう十年になるね。)
whine はおぼえておくと役に立ちます!
Stop whining!(泣き言はよせ!)のようによく使います。