With her marriage, she had leeway in terms of both money and time in her life.
ご質問ありがとうございます。
"With her marriage,"＝「彼女は結婚により、」
"she had leeway in terms of both money and time in her life."＝「お金と時間の両方に関して余裕がある人生になった。」
同じ文脈で "leeway" 以外を使う文章にすると: "After she got married, she could afford to live comfortably without having to worry about the lack of money or time" とも言えます。
ご参考に。
She got married and found herself with lots of leeway in terms of money and time.
Once she got married, she found herself with lots of extra time and money.
leeway を使うなら、次のように言えると思います。
ーShe got married and found herself with lots of leeway in terms of money and time.
「彼女は結婚して、お金と時間にたくさんの余裕を見つけた」
または次のようにも表現できます。
ーOnce she got married, she found herself with lots of extra time and money.
「彼女は結婚すると、たくさんの余分の時間とお金の余裕を見つけた」
ご参考まで！
アメリカ合衆国 
カナダ 
