That is a very loaded question. Blockchain is the technology on which cryptocurrencies are built. There is tons of information out there on blockchain and cryptos and I can't possibly answer this question effectively without more clarity as to what exactly you are looking for. If you are interested in blockchain/crypto - I suggest joining our Discord and talking with members in the crypto channel. We have several members who are very well versed in this area and have been helping other members navigate these waters.
There are links to resources for beginners, and are happy to answer any question. If you are not interested in signing on to Discord, I could post some links to beginner resources that would be helpful. Just let me know.
Mat