I see in the blockchain, there is Bitcoin and Ethereum that we can save in there. And I see a button that will exchange Bitcoin into Ethereum, maybe that is what you mean. I think it is save because the system is proceed your transactions not people. You may see some exchangers that will buy or sell money currencies out there. They are legit people and sometimes can scam you. But no need to worry, because all you need to do is finding a trusted exchangers. You can find it on forum or ask in some facebook groups.