can you explain mrd to me?

Required minimum distribution (RMD) is the minimum withdrawal you are required to take out of your IRA (including SEPs, SARSEPs, and SIMPLE IRAs) or employer-sponsored retirement plan (such as pension, profit-sharing, 401(k), 403(b), or 457(b) plan), starting at a certain age.

See this TurboTax Help.

What is the nature of the pension distribution that TurboTax is asking about?  If the pension distribution is one of those listed above, the pension plan is subject to a required minimum distribution.

Are you getting a pension?  When you turn 73 it will ask you if it is the RMD.   Say yes and enter the amount as the RMD amount. The pension doesn't need to calculate any RMD. Anything your pension pays you is considered to be the RMD. Traditional pensions automatically fulfill the rules of an RMD. So just enter the same amount in box 1 for the RMD for each 1099R. 

Do you have any other retirement accounts?  Like a 401K or a IRA?  You need to take the RMD each year from those too when you turn 73.    The plans should tell you how much you need to take out.