When we develop software as a team after sometime
You will have somethings in the code that are not working as expected. These unexpected behaviours are called issues or bugs.
There will also be a plan to add functionality to the product (code) called feature work items
These bugs and feature items need to be tracked. Like when will an issue be fixed, some need to be fixed immediately like security issues. Some can take some time. So there is priority in the execution plan.
And who in the team will work on what issues.
All the things can be tracked with issue tracker softwares like Asana (https://asana.com) and alternative softwares like https://alternativeto.net/software/asana/
A developer will open the issue tracker and find what have to be done right now and starts working on it. He will set ETA for each issue assigned to him, i.e. By what time the issue will be fixed. Once fixed they will assign to the tester who opened the issue. The tester will verify the fix and close the issue.