Girls, help me understand. They removed the pessaries at 38 weeks. I h…

Girls, help me understand. They removed the pessaries at 38 weeks. I had an ultrasound before that. The cervical length was 21mm. The internal opening widened to 11.6 mm. The external opening is closed. What does it mean when the internal opening widens? I'm a first-time mother. I don't know much and don't understand. After removing it they said the opening is 1 finger wide. How long will it be like this?