What is the statute of limitations on a credit card bill?

It will vary by where you live, ( what county, and if in the US what state)

Cook county Georgia

Its 4 years from the date of last activity. This is the period in which the creditor has to file suit. The debt itself doesn't expire.

I have gotten a summons to go to court. I was told I have 30 days to reply or they will get a judgement. How can they do this if this card hasn't been used in 7 years.

File notice of Intend to defend and go that day to court. Tell the court that the SOL has pass and request dismissal based on those facts.

What is COL?

SOL not COL. Statute of Limitations.

They hope you won't respond and they can get a default judgement so they can go after your assets. So you do a Yet said. You file a Notice to Defend. If the SOL has truly passed, then the case will be dismissed.

BUT, as I pointed out earlier, the debt itself doesn't expire. They can still dun you for the amount owed, they just can't sue you. You DID borrow the money and you DID promise to pay it back.