What to do if I recently received a summons for a credit card debt that I accrued about 5 years ago and am not sure what to expect?

You will need to file an answer to the complaint (the complaint is the lawsuit attached to the summons) with the court and serve a copy by mail on the opposing party or the opposing party's attorney within the time set forth in the summons.  If you don't timely file your answer with the court and serve it on the opposing party the opposing party will file a default with the court and will get a default judgment.  A default judgment means you will have lost the case.  If that happens, you will need to file a motion to set aside the default.  If the judge grants your motion to set aside the default, the case will be back on track and litigation will continue.

To avoid that problem, timely file your answer to the complaint and serve a copy by mail on the opposing party.  At the law library look in the index of Pleading and Practice for answer to complaint.  This will give you the general format for an answer to a complaint which denies the allegations in the complaint.  At the end of the answer is the verification which you sign and date under penalty of perjury attesting to the veracity of your statements in the answer.  File the answer and verification with a proof of service with the court and serve a copy by mail on the opposing party.  You can either use a court form proof of service or you can write your own.  The proof of service verifies the date of mailing to the opposing party.  If you write your own proof of service, it just says that you are over eighteen and the attached documents were sent via first class mail unless stated otherwise to ___________ (name and address of opposing party or opposing party's attorney) on _______ (date).  You sign and date at the bottom.  The date you sign should be the same as the date of mailing and the same date you file your documents with the court.