Overview

See Usage limits, billing, and administration in the docs.

Including how many concurrent jobs.

Billing

From About billing for GitHub Actions

If you want to use GitHub Actions beyond the storage or minutes included in your account, you will be billed for additional usage.

GitHub Actions usage is free for both public repositories and self-hosted runners. For private repositories, each GitHub account receives a certain amount of free minutes and storage, depending on the product used with the account. Any usage beyond the included amounts is controlled by spending limits.

Limits

Product Storage Minutes (per month)
GitHub Free 500 MB 2,000
GitHub Pro 1 GB 3,000

From the GitHub Pricing page - if you go from Team to Enterprise, the automatioj minutes goes up to 50,000.