Iteration is the process by which something (such as a sign) is replicated or reproduced;
Iterability is the ability to repeat or repeat; to be able to repeat or reproduce over and over again.
It is generally accepted that this is an essential feature of the signs.
Charles Peirce explicitly supports this view:
“The state of existence of a representamen (or simply a sign) is that it is capable of repetition.” (CP 5.138)