5 digit pin

I was finishing my tax return when TurboTax asked me to create a 5 digit pin number. Can anyone please tell me what this is? In previous years, I just mailed my taxes. This year, I am considering filing it electronically. Will I have a problem if this is the first time I create the pin? Will I have to do this every year I file it electronically?

 

Thank you for your help.