Processing cost of a Python script

Where do you run Python?
If you are running on EC2, you will incur EC2 startup time and data communication charges.
In the case of Lambda, the fee is based on the time the script is executed.

https://aws.amazon.com/ec2/pricing/?nc1=h_ls
https://aws.amazon.com/lambda/pricing/?nc1=h_ls

In addition to @Riku

EC2 Instances: If you are running your Python script on Amazon EC2 instances, you will be charged for the usage of those instances. The cost will depend on the instance type, the duration for which the instances are running, and any additional resources you use, such as storage or data transfer. EC2 pricing is based on an hourly rate for the instance type you choose.

AWS Lambda: If you use AWS Lambda to run your Python script, you are billed based on the number of requests made to your function and the duration of the function's execution. AWS Lambda pricing is based on the number of invocations, the total duration (calculated in milliseconds), and the amount of memory allocated to your function.

AWS Batch: If you are using AWS Batch to run your Python script, you will be billed for the compute resources used by your batch jobs. The cost is calculated based on the number and type of instances used, the duration of the instances, and any additional resources consumed.

AWS Glue: If you are using AWS Glue to run your Python script for data processing or ETL (extract, transform, load) tasks, you will be billed based on the number of Data Processing Units (DPUs) consumed during the job execution. AWS Glue pricing is based on the number of DPUs used per hour.