This is super easy
But do just like daniellogin said and go trhoug a couple of tutorials so u understand the basics.
There are multiple ways you could set this up.
I would do it as follows:
Player only goes left right.
set up a row of parent objects with inside the different color combinations.
The colors inside will have the 2d colliders. the parents fsm activates the children based on a random number. (random number generator) those numbers you will associate with the children.
this way you will have random colors active.
all of this is inside the main parent that moves to the bottom via translate.
once out of the screen at the bottom disable and set position back to the top. activate again and you will have a new collum that moves down.
For the player u simply use a couple of collider actions check own color vs color hit.
This is the overall idea I would use. Of course, there are more things to do than I have listed here.
Hope this helps.