Remaining Amount
Balance
noun
The remainder amount is the remaining amount, aka the balance.
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.
念のため、ICカードのチャージ残額を確認しておくよ。
Just in case, I'll check how much money is left on my IC card.
やばっ、残額、五百円もないわ。
Oh no, the remaining amount is less than 500 yen.
残額は全て寄付します。
I will donate all the remaining amount.