Holy water is a sacramental associated with the Church’s prayer and a reminder of Baptism. Using it with the Sign of the Cross can help turn an everyday action toward God.
A little more context
A sacramental is different from a sacrament. It disposes us to receive grace and cooperate with God; it is not magic and does not give an object independent spiritual power. Ask your parish about obtaining holy water and using it respectfully at home.
A practical beginning
If you keep a small container at home, place it where it can be used reverently and safely. Let it prompt a short prayer rather than treating the container as protection that works without faith or conversion.
Source & further reading
Catechism 1667–1671: sacramentals (opens in a new tab)↗Teaching summaries are introductions. Follow the linked Church source for its fuller context.