Here is a single color palette for an app learning IELTS, along with color names, hex codes, and a brief description for each color:

1. Midnight Blue
   - Hex Code: 
          
          #191970
       
   - Description: This deep, rich blue color resembles the night sky and evokes a sense of calmness and concentration, ideal for an app focused on learning IELTS.

2. Goldenrod
   - Hex Code: 
          
          #DAA520
       
   - Description: A warm and vibrant yellow color, similar to the hue of goldenrod flowers. It represents optimism, intelligence, and encourages motivation and enthusiasm in the learning process.

3. Slate Gray
   - Hex Code: 
          
          #708090
       
   - Description: A neutral and sophisticated gray color with a slight bluish tint. It creates a professional and serious atmosphere, perfect for an app that aims to enhance IELTS skills and knowledge.

4. Emerald Green
   - Hex Code: 
          
          #008000
       
   - Description: This lively and refreshing green color represents growth, harmony, and balance. It symbolizes progress and learning, making it an excellent choice for an IELTS learning app.

5. Coral
   - Hex Code: 
          
          #FF7F50
       
   - Description: A vibrant and energetic shade of orange-pink, reminiscent of coral reefs. This color stimulates creativity, enthusiasm, and encourages active learning, making it suitable for an engaging IELTS learning app.

Note: You can adjust or modify the shades and hues of these colors according to your preference or specific design requirements.