Environment variables are a way to store reusable data and sensitive information like API keys, database passwords, and other settings that you can use in your Python code. These variables are ideal for when you don’t want to hardcode sensitive information in your code. Instead, you can store them as environment variables and read them. You can manage your environment variables by clicking the “Environment variables” button on the bottom bar of the editor.
Environment variables button

The environment variables button on the bottom bar.

This will open a page in which you can add and delete environment variables.
Environment variables page

The environment variables page.

Within the environment variables page, you can add a new variable by clicking the “Add variable” button. Once you’re done adding your variables, click the “Save” button to save them. Then, you will be prompted to restart your environment to apply the changes. Finally, you can use your environment variables in your Python code by reading them from the os.environ dictionary. 
import os

your_env_var = os.getenv('YOUR_ENV_VAR')

print(your_env_var)