How to ignore any source components to be pulled or push from or to Scratch Org?

If you check your local SFDX Project Directory, then you can see that there is a file named as ".forceignore". This file is basically used for ignore source component(s) tracking.

• IGNORE SOURCE COMPONENT(S) FOR PULL OPERATION.

1. If you want to ignore any file(s) to be pull from Scratch Org to your local project, then just copy paste your file name (with extension) in your ".forceignore" file. For example say you have create a class "TestIgnoreClass.cls" in your Org for any R&D purpose and you don't want to pull it in your local project, so just write the name "TestIgnoreClass.cls" under your ".forceignore" file.

• IGNORE SOURCE COMPONENT(S) FOR PUSH OPERATION.

1. If you want to ignore any file(s) to push from local project to Scratch Org, then you have to give absolute path of that file/folder [Path will be started from your root directory]. For example say you have a class "TestIgnoreClass.cls" in your local project and you don't want to push it to your scratch Org, then just write the path of that class "force-app\main\default\classes\TestIgnoreClass.cls" under your ".forceignore" file.

Note: If you have multiple classes to be ignore then just write down the file names (pull operation) / file or folder path (push operation) with extension and separate the file/folder by placing them in new line.