Legal Question in Civil Litigation in Texas

It means that you need to file a written answer; file it with the clerk's office. This will prevent the plaintiff from taking a default judgment against you.

You really should consult with an attorney first, in case there is a question of jurisdiction. If you file an answer, you're stuck in that court, and you may thereafter be precluded from raising issues of venue and jurisdiction.

The request for disclosures will also need to be answered eventually (the deadline is 50 days after you were served).