What are these colored tabs in my art supply kit?
You probably have the 101-piece set, the 126-piece set doesn't appear to include any supplies that look like those.

Here's the product image of the 101-piece set, for reference:



This set contains, among other things


  
  12 oil pastels
  12 soft pastels
  10 watercolor cakes
  


Based on the product image, the oil pastels are likely the items shown leaning in front of the bag in the center, with the blue and white wrappers. They should look and feel kind of like crayons. I've only seen these sold in cylindrical form which also matches with the photograph.

So instead, your first image would be the soft pastels. They usually come in rectangular form, and feel like chalk.

The second image is most likely the watercolor cakes. Although the colors and amount seems to differ from the product page I found, this is the only type that makes sense. The cakes are compressed pigments which you use by adding water (typically by mixing on the palette).