Have you ever heard about TDS, what it is?

Yes. As you said it is Tax Deducted out of our sources of Income in advance.

Simply it is a Income Tax related term, as your tax is going to be deducted proportionately from the sources of income you are receiving before filing the returns and accessing the income. Once accessed and finalised the tax, if the tax deducted excessively returned to you otherwise you need to pay the difference amount the IT department. Thanks.