Quantum computing is not a faster version of contemporary computing machine. It is based on a totally different algorithm basis (e.g. Shor's algorithm), replies on physical phenomena absolutely different from those underpinning classical computing, and, surprisingly, is meant to be used not as a replacement of modern computers but as their supplement since classical computing would be good at some areas and quantum in others.
Superposition and entanglement are two characteristics from the quantum world that are used for quantum computing. Instead of being in the state of 0 or 1, a particular system may be in infinite number of states at the same time. Only when we check it the system takes a state of either 0 or 1. Entanglement allows for knowing what is a property of a particular system without verifying it (it is sufficient to measure its entangled counterpart).
Problems that grow exponentially in their complexity are difficult to solve by classical computing. Since quantum computing can run calculations simultaneously such problems would be much easier to crack.
More about quantum computing you may read in Chris Bernhardt’s “Quantum computing for everyone” (2019).