Can anyone help me in Knowing which Programming Language knowledge is required for ASD and for creating the Workflow in vCO
You will need to know scripting languages.
Java, pearl, python etc. There is no specific recommended one as one has to choose what they are comfortable with.
This is not exact.
ASD is a user interface that allows you to create services, services catalog items that are tied to vCO workflows. It does not provide you with a scripting language.
I never had to use any scripting in ASD, there may be some to evaluate inputs or display some labels but this may be limited to this simple use cases.
The only "Building machine Workflow" I know where you can add custom code is in the (Windows based) IaaS Workflow designer which as nothing to do with Advanced Service Designer (ASD).