Ethereum is a cloud computing service. It has two advantages over other cloud computing services:
(1) it is extremely highly available
(2) the person who uploads a program cannot modify that program afterwards and has no special admin access over that program's data storage; furthermore all data stored including program code is publicly viewable.
Because the program author has no admin privileges, users don't have to worry about the service provider abusing their admin privilages to secretly modify the database (which may otherwise be a concern for high-value applications such as, e.g. vote-counting, e.g. a database that stores bank account balances, etc).
The disadvantages are (1) it is much more expensive compared to other cloud computing services, (2) since the uploader doesn't have admin access, they can't fix bugs, and since everything is transparent, it's hard to store secrets.
It takes some time to wrap your head around the blockchain, first you have to understand Bitcoin , then you will have no issues understanding Ethereum. But I tell you one thing, once you understand it, you will not stop thinking about it.
I dream about blockchains. Yeah it's true, not only the technology is interesting but also the community and all the ecosystem behind cryptocurrencies.