Limited edition means that the number of produced art prints is fixed to a specific value. Most art print publishers restrict themselves to a maximum print run of 850 copies. But this is a definition for marketing reasons and not required by law. There are upward as well as downward deviations from this on the art print market.
Limited edition art prints are usually signed in pencil by the artist personally and are labeled with a number, i.e. 25/350, which in this instance means 'art print number 25 from the edition of 350 copies'. Frequently 'Limited Editions' are supplied with a 'Certificate of Authenticity' from the publisher which contains the name of the artist, the title of the art print and data about the edition size. Also the specific number of the acquired print may be registered on the certificate.