Hey Luis, thanks for reading the article! To answer your question. It’s about increased functionality/operations. Bitcoin was the first blockchain. It provided/s one specific function, peer-to-peer electronic Bitcoin payments. Ethereum then came along, introducing smart contracts and offering a platform that enables developers to build and deploy other decentralized applications of far greater functionalities. So, rather than just providing users with a set of predefined operations — like Bitcoin transactions — Ethereum let users develop their own operations with the complexity they wish.
What makes Ethereum a second generation blockchain is that it provides developers an enormously powerful shared global infrastructure to build almost anything they want. To create markets, store registries of debts or promises, move funds in accordance with instructions given long in the past (like a will or a futures contract) and many other things that have not been invented yet, all without an intermediary or counterparty risk.
That’s not to say that Ethereum is better than Bitcoin. The two blockchains just have different purposes/functions.