A qubit, like an electron, can have a property called 'spin'. We simplify this to 'spin up' (|↑⟩ or |1⟩) or 'spin down' (|↓⟩ or |0⟩). Before measurement, a qubit exists in a superposition - a combination of both states, represented below by faint up and down arrows. Measurement forces it into one definite state.
Multiple qubits can become entangled. Their fates are linked. Measuring one instantly influences the state of the others based on the entanglement type: 'Same Spins' (all identical), 'Opposite Spins' (N=2 only, opposite results), or 'Alternate Spins' (spins alternate along the chain).