What-is-blockchain-technology?

YouTube has some good videos explaining that technology. There is not enough space in this comment section to provide an adequate answer.

It simply means every group (company) in a supply or financial chain knows what everyone else is doing as to basic things. In a simple way, all of the computers are connected so nobody can change anything without other records existing. Wiki has a good summary.  https://en.wikipedia.org/wiki/Blockchain

Isn't it the thing that verifies cryptocurrency by holding data on multiple accounts across all accounts.

block and chain -- refers to technologies that existed before electronics.  A real block and chain was used in the past to lift heavy objects ---  some still use it to lift engines out of cars to work on them.  You attach a hook to the object to be lifted, then physically pull on the chain to lift the object.  ==  More manual labor involved than electronics.

YouTube has some good videos explaining that technology. There is not enough space in this comment section to provide an adequate answer.