How do I see what exactly this charges for? It seems to be recurring once per year, but I don’t know what it is for

You should have gotten an email receipt sent to your Apple ID email address. In addition, here is a one-stop link for billing questions→Subscriptions and Billing - Official Apple Support. You can review your purchase history to see what you were charged for, cancel subscriptions and request refunds.

I also had the same question, and found out exactly what apple services I was paying for. Thank you!

But, it only goes back 5 months. Is it possible to go back further?

What says Apple Services on the phone? Can you post a screen shot? Every Apple service in my purchase history states exactly what the purchase was for. for example, AppleCare+, iCloud Storage, the title of any music I downloaded, Apple TV+, etc.

Did you follow the instructions to review your Purchase History on your phone?

I also had the same question, and found out exactly what apple services I was paying for. Thank you!

But, it only goes back 5 months. Is it possible to go back further?

It should go back 6 months including the most recent charge, which is the limit on how far back you can request a refund.