The Daily Challenge games have some numbers on the blocks. To remove blocks with numbers, you need to match them with other blocks and make squares and lines as many times as indicated on these blocks.
For example, if the number is 2, then you need to make a square or line with these blocks, and the number will fade. Then form another square or line with these blocks, and the blocks will disappear.
A Daily Challenge is completed when you've reached the necessary score. You can see this score in the top left corner of the grid.
The Daily Challenge score is calculated depending on your average score from regular games. The higher the average score in the regular games, the higher the score you need to achieve in the daily challenge games.