金遣いが荒いです。(かねづかいがあらいです。)
Kanedukai ga arai desu
You are a spendthrift.
What does Kanedu(zu)kai ga arai mean?
In English, this means maybe spendthrift, extravagant,spender.
Let’s see some examples
彼は良い人だけど,金遣いが荒い。
Kare wa you hito dakedo kanezukai ga arai.
He is a good person, but he is a big spender.
彼は結婚してから浪費家になった。
Kare wa kekkon shite kara rouhika ni natta.
When he married she became a spendthrift.