What "weed killer" means in gardening

Weed killer is a chemical or natural substance used to control or eliminate unwanted plants or weeds in a garden or lawn. It works by inhibiting the growth or killing the roots of the unwanted plants while leaving the desirable plants unharmed. Weed killers come in different types, including pre-emergent, which prevent the germination of weed seeds, and post-emergent, which kills existing weeds. However, excessive use of weed killers can harm the environment and the health of other plants, animals, and humans, so it should be used with care and following the instructions.