ChatGPT's code interpreter is mostly used as a calculator / graphing calculator. It can run arbitrary Python code, but it is limited in practice because it can't (e.g.) make external web requests or install arbitrary packages.

This is meant to be usable for those use cases, but also to allow apps/agents to make API requests, load data from various sources, etc. It can also run in a company's cloud account, for compliance situations where they are running inference on their cloud account and want a ChatGPT-like code interpreter where data never leaves their VPC.