Get your taxes done using TurboTax

I'm still trying to understand this.  I got to a question about underpayment penalties that I don't know how to answer.  
Title on Page is Actual Withholding and it says:
The IRS treats your total federal income tax withholding (from wages, interest, dividends, gambling winnings, etc.) as being paid in four equal quarterly installments.
For purposes of figuring the underpayment penalty, you may elect to treat the tax withheld as paid when it was actually withheld. Would you like to do this?
I don't know if I would like to do this or not.  Don't really understand.  Can you help
Thanks
Paula