The Czech Easter Monday tradition using a braided willow switch is called pomlázka.
A pomlázka is a braided switch traditionally made from young willow branches. On Easter Monday, boys and men visit girls and women and symbolically tap them with it. In return, they may receive decorated eggs, sweets, ribbons, or drinks. Modern practice varies greatly, and many people treat the custom as folkloric rather than literal.
The willow is associated with spring growth and vitality, which helps explain the custom’s symbolism. The word can refer both to the switch and, in some contexts, to the associated practice. Czech Easter eggs are often called kraslice, but that term names the decorated eggs rather than the willow-switch tradition.
Pomlázka is particularly associated with the Czech lands. Related Easter Monday customs occur elsewhere in Central and Eastern Europe, including Hungary’s locsolkodás, but sprinkling with water or perfume is not the defining feature of pomlázka.