I have a table in the database which has a large number of columns. I know that EasyAdminBundle is out there and I used it in the past to create forms based on database tables. How can create this based on Entity? So that I can generate the forms automatically and no populate them manually.
You can use the Symfony Maker Bundle. With this bundle, you can generate code if you are using a version of Symfony later than 3.4. For older versions you can use Sensio Generator Bundle.
In your case, install the Maker Bundle with composer:
composer require symfony/maker-bundle --dev
Then run this command (and follow the steps) to create your form:
php bin/console make:form
To see all make commands you can use, run php bin/console list make