What does lincoln say that the people at the dedication of soldiers national ceremony could not really dedicate, consecrate, or hallow that ground.

What you are referring too is the Gettysburg address. But perhaps maybe you haven't heard it all over.

Lincoln explains in his speech that it is the soldiers who have given their lives, and who have fought with such valor in what they believed in, that have hallowed this ground. Soldiers on both sides, as the states which turned against the union, remained as stars on the union flag.

In other words, it is not the piece of paper that hallows the ground. Not the speech or any other source or action. It is the dedication of the men who fought there that hallowed that ground

If you wish to learn more about this, I recommend going to Gettysburg Pennsylvania just as I have. The town features great restaurants and attractions and you can learn so much from the museum and a trip to the battlefield.