what is a blue card? (Texas)

What is a blue card? I start my classes in 2 weeks and my advisor just told me about that card which is the first time i’m hearing about it. She advised me that I wouldn’t be able to take foundations & patho together for the first term because I didn’t have this card and that it would take time to receive it. My financial advisor on the other hand, was willing to combine my classes in order for me to start core in January, but that it would add 10 grand to my tuition. Her reasoning was that it would consider me as full time (i didn’t know i was part time). My questions are what is this blue card and why I would be charged an additional $10,000 just for taking 2 classes together.

• I also transferred every credit I could including a core credit (46/120 credits)