The precept is: “Your deeds are your monuments.” I think the precept means that your deeds are what will stand out. Your deeds are what people will remember you for. Your deeds are not made of stone, but they are still monuments. Monuments might be defined as statues, or special structures. Your deeds are still monuments, but in a different way. In a different way, monuments might be defined as something people remember. That’s where the deeds and monuments thing comes in. People remember your deeds.
Some people won’t remember the bad things people do. We remember the main thing, the deed. Here is an example: Terry Fox. No one exactly remembers the streets he ran in or every person he has met. But, we remember he fought for cancer. This is what I think this precept means.