it's basically expectations for what is about to happen. If you follow Ethereum closely you will know that it is going through some "phases" these "phases" are basically protocol updates that are meant to make the network better, more stable more efficient and basically fit for the future. Some of these updates are very close and that's one of the reasons why ETH is gaining at the moment. These protocol updates will make a lot of changes as well not only to the protocol itself, but to the competitors of Ethereum too. You have for example Ethereum changing from mining to PoS. PoS is Proof of Stake which means that instead of mining to validate transactions you will have to just keep some Ethereum and you'll be able to simply validate transactions yourself, and gain some coins in return.