What does valid from mean on a credit card and whats an issue number?

• interest credit card offers
• online secured credit card
• tax credit number

Im trying to buy something offline and it says i need a valid from date its not an expiration date i know because i ordered alot of things offline before and it never said i needed anything like this and what the heck is an issue number this doesnt make any sense why cant it just be simple like how i ordered all my stuff offline.

What does valid from mean on a credit card and whats an issue number?