So how AWS generated 879 INR rupees bill to my account.

I d recommend to look into this https://repost.aws/knowledge-center/cost-explorer-analyze-spending-and-usage

Hello @suhas

You can use the Bills page to see your monthly chargeable costs, along with details of your AWS services and purchases made through AWS Marketplace. For monthly billing periods that haven't closed (the billing status appears as Pending), this page shows the most recent estimated charges based on your AWS services metered to date.

I highly recommend that you setup a billing alert where you can have the system keep track of any expenses in your Free Tier account and send you an alert notification when you meet the treshold. Example, you can setup a 100 Rupees threshold and if you get to that point, an email will go out.

https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/monitor_estimated_charges_with_cloudwatch.html

You can also download a usage report:

Sign in to the Billing and Cost Management console at https://console.aws.amazon.com/billing/home#/

In the navigation pane, choose Cost & Usage Reports.

Under the AWS Usage Report section, choose Create a Usage Report.

On the Download usage report page, under Services, choose the service that you want to view usage for.

Choose the Usage type.

Choose the Operation.

Choose the Time period for the report. If you choose Custom date range, you need to specify the Date range for the report manually.

Under Report granularity, choose Hourly, Daily, or Monthly.

Choose Download, and then choose XML Report or CSV Report.