Getting Code coverage is very crucial part while deploying the apex triggers or class from Sandbox to Production org.
Inspecting Code Coverage
After running tests, you can view code coverage information in the Tests tab of the Developer Console. The code coverage pane includes coverage information for each Apex class and the overall coverage for all Apex code in your organization.
Also, code coverage is stored in two Lightning Platform Tooling API objects: ApexCodeCoverageAggregate and ApexCodeCoverage. ApexCodeCoverageAggregate stores the sum of covered lines for a class after checking all test methods that test it. ApexCodeCoverage stores the lines that are covered and uncovered by each individual test method. For this reason, a class can have multiple coverage results in ApexCodeCoverage—one for each test method that has tested it. You can query these objects by using SOQL and the Tooling API to retrieve coverage information. Using SOQL queries with Tooling API is an alternative way of checking code coverage and a quick way to get more details.
For example, this SOQL query gets the code coverage for the TaskUtil class. The coverage is aggregated from all test classes that exercised the methods in this class.
SELECT ApexClassOrTrigger.Name, NumLinesCovered, NumLinesUncoveredFROM ApexCodeCoverageAggregate
WHERE ApexClassOrTrigger.Name = 'TaskUtil'
