Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
As Palcouk wrote, check your account at https://account.microsoft.com/services. One possibility is that you signed up for a trial version of Microsoft 365 and forgot to cancel. For more on canceling a subscription; see https://support.microsoft.com/en-us/office/cancel-a-microsoft-365-subscription-46e2634c-c64b-4c65-94b9-2cc9c960e91b.
The following article may (also) be relevant: https://support.microsoft.com/en-us/account-billing/how-to-investigate-a-billing-charge-from-microsoft-398c5328-364c-d5e4-ea8f-f5ad60562a93.