The company bringing the suit will win by default, meaning everything it alleges in its petition will be deemed true, if the defendant failed to file an answer denying the allegations and fails to appear.
The company bringing the suit will get a judgment for the amount they claim is owed, and can then seek to enforce the judgment through various ways to recover the money. Further, a judgment can be filed as a lien against property the defendant owns or will own in the future.
With credit card suits, often times there are many deficiencies in the pleadings and in the proof that, if contested, can defeat the lawsuit. Also, some credit card suits are brought by collection companies that obtain the debt long after the card is defaulted, and the suit is filed after the legal deadline to do so. None of these challenges can be made if a defendant fails to answer or appear.
You should consult with an attorney about the allegations made and your defenses. You should also consult with an attorney about your deadlines to respond and other options you may have, including counterclaims against the credit card company.