So, while a bit represents just 1 or 0, one Qubit represents an array of possibilities and all can be calculated simultaneously taking probabilities in account. So, a particle momentum looks different to different observers and the particle has several states simultaneously. For one observer, the probability of the particle momentum could be state for that observer. That is why one subatomic particle can have different states -and probabilities, at the same time. When you combine Qubits, that combination holds an exponentially larger amount of information than bits.
Subatomic logic is much more powerful than binary logic.
You can process complicated information faster. Its main applications are encryption, decryption, modeling, databases, voice recognition, structure recognition and artificial intelligence, plus others yet non-existent applications. Simple computation like word processing, would not improve its performance with Quantum Computing. Image processing and artificial intelligence for diagnosisng certainly will. Quantum Mechanics has also proved that two entangled particles share its existence.