Ethereum is a decentralized platform which allow you to build decentralized applications with using tokens as payment method. Ethereum provides a technology that is useful for a lot of application such as digital currency, electronic vote, etc. Like bitcoin, ethereum has value because a lot of people believe that it will be widly used in the future, and buy the cryptocurrency linked to it (ether) because its price will grow if more and more people buy it. This price comes from the trust people put in this technology, the belief that it is secure, and the assumption that it will be used more and more in the future.
As for the words you don't understand, ethereum is a very complex technology for people not used to crypto currency, and I personnaly don't understand everything to it. It is not something you can understand in few minutes.