This article explains the Signature block that can be added as a block to design an app.
Click on the block and start editing on the panel that appears on the right side.
This is what appears as the name of the input block to the end-user.
This is the text that goes below the input block to help the user.
By default, users can edit the signature. If you don't want users to modify the signature, turn off the option "Allow Signature to be changed by user".
Tick this option if you want the user to compulsorily sign the form.