Linting is an automatic check that looks through code for common mistakes and agreed style rules. It is like a careful proofreader pointing out small issues before someone reads the finished page.
A lint tool might warn that a variable was never used or that a line does not follow the project's formatting rules. Fixing these warnings can make code easier to maintain and may prevent some simple bugs.
Linting cannot understand every decision or find every problem. It gives suggestions based on rules that the project has chosen.