Pedipalps are the two "feelers" on a spider's face. Some spiders seem to have ten legs and not eight, because these pedipalps look like an extra pair of legs. But the pedipalps are more similar to arms. Spiders often use these to hold small animals (for example crickets) for them to eat.
Male (father) spiders also use pedipalps for mating- for making baby spiders. The male spiders make some silk, put sperm onto the silk, and then put their pedipalps into the sperm. The pedipalps then hold the sperm, and the spider can use it to mate with a female (mother spider) by putting them inside of her epigynum.