Tessera sanitaria

I suspect it means the kiosk/office in your local hospital where you would have to go to pay for any treatment/prescriptions. Have a look at your ASL site and it will probably give a list, with opening hours etc

If they are the same as our Ligurian ones you don't need to have them validated but you can choose to go to the local Agenzia delle Entrate office to have them activated so you can use them as  a Carta Nazionale Servizio online - ie a card letting you access certain information about yourself held by the Agenzia delle Entrate.

This link may help - http://sistemats1.sanita.finanze.it/wps/content/portale_tessera_sanitaria/sts_sanita/home/il+cittadino+e+la+tessera/come+si+attiva+la+cns The information provided seems to vary from region to region, but hopefully it will help.