Hey! I am a beginner trying to understand how DataHub works. Can anyone give me a rough idea of how much it costs to operate a data catalog solution based on DataHub (sorry if there is any mistake in the wording of my question)?

Likely depends on your underlying infra, could be in the tens of dollars to hundreds of dollars per month. If you want to do more exact calculations, you can look up the costs of running a EC2 instances + kafka + a DB for your needs and calculate the exact cost per month using something like the AWS cost calculator(https://calculator.aws/#/addService).