If you see 'apple.com/bill' on your billing statement

Apple.com/bill appears on your billing statement when you buy an app, music, movie, or other content from Apple. It also appears when a subscription renews and when a family member buys apps or content from Apple.

How to see what you were charged for

To see your purchase history, go to reportaproblem.apple.com.
Sign in with your Apple Account.
A list of purchases appears. To see family members' purchases, select the Apple Account button and choose a family member.
To see the full receipt including tax, tap or click the date. Multiple purchases, including subscriptions, might be grouped onto one charge.

If the charge is for a subscription that you no longer want, you can cancel the subscription. Find out where else you can view your Purchase History.

If you still can't identify the charge

If you can't find a matching charge at reportaproblem.apple.com, you can find out if you used another account to make a purchase.

Search your email for the words "receipt from Apple" or "invoice from Apple".
Look for a receipt that matches the amount that you see on your billing statement.
On the receipt, see what was purchased and which Apple Account was used.
Check if the Apple Account in the email is different than what you used to sign in to reportaproblem.apple.com. If it's different, use this Apple Account to sign in to reportaproblem.apple.com and review your purchase history.