Establishing pull request merge conditions
You can require pull requests to pass a set of checks before they can be merged. For example, you can block pull requests that don't pass status checks.
About protected branches and required status checks→
Protected branches ensure that collaborators on a repository cannot make irrevocable changes to branches. Required status checks ensure that all required CI tests are passing before collaborators can make changes to a protected branch. Branches within repositories that belong to organizations can be configured so that only certain users, teams, or apps can push to the branch.
Configuring protected branches and required status checks→
You can enable protected branches for limiting branch manipulation, as well as enforce required status checks before a branch is merged in a pull request or before commits on a local branch can be pushed to the protected remote branch.