Please clarify one question for me. From other sources I've understood that what we call today quantum computer basically does something random which can't be r

Please clarify one question for me. From other sources I've understood that what we call today quantum computer basically does something random which can't be reasonably reproduced on conventional computers and because of that we declare that this process was quantum computing. But you can't do specific calculations on them - have some input data, some algorithm and receive usable and verifiable result faster than on conventional computer. Is this in general correct or not?