How can one make an object appear randomly?
Thanks for your question and welcome to the forum!
Do you want it to appear randomly in a specific area or at a specific time? The general idea is to have a transparent object that generates the new object, and to use a timer as well as a random number generator and a comparison to decide whether an object should be created or not.
If you give me a few more details, I can create an example mini-game for you.