Retirement tax questions

Thank you evelynm! just one quick follow up question. i am a bit confused with the sentence below regarding not any social security tax. my question is once i retire and start collecting social security do i get taxed on those amounts? i don;t believe i am paying taxes on social security via my paycheck, right? 

 

You will owe income tax on 401(k) distributions when you take them, but not any Social Security tax.