Hi @LudmillaChellemben, we advise you to search through the community and share the attempts that you made to solve this problem.
If you’re stuck then the people of the community will be able to assist you for sure.
Currently, you can check out our docs: https://learning.postman.com/docs/postman/variables-and-environments/variables/
Community search: https://community.postman.com/search?q=Environment%20variables
One of the posts that already suggests a solution: Set array from environment variable for request body in postman