Test automation allows teams to remove the slow and manual testing cycles related to software development. Test automation can include such things as:
It increases the code quality.
It shortens feedback loops.
It tells if your change broke some previously working code.
These tests are typically executed by a build automation tool, for example Jenkins. Easy and quick tests should be ran right after building (compiling) your application, such as unit tests and static code analysis. Also many of these tests can be run in parallel, decreasing the overall time taken to run the tests.
Check out these great links which can help you dive a little deeper into running the Test automation practice with your team, customers or stakeholders.