A hedge trimmer is a garden tool built to trim, shape, or prune hedges, shrubs and bushes — replacing manual shears or secateurs with a powered cutting mechanism.
A cordless hedge trimmer uses a battery (usually lithium-ion) rather than a power cable (corded) or a petrol engine. This gives you freedom of movement: no cords to snag or limit reach.
Internally: the battery powers an electric motor which drives one or two reciprocating blades (teeth on a bar) that open and close rapidly — the “dual-action blades” common in many trimmers. As you sweep the tool across a hedge, those blades slice through stems and leafy growth.