Signing another person's key means you are giving trust to that person. Before signing a key, you have to carefully check the key's fingerprint to be sure that the key really belongs to that person.
Beste norbaiten gakoa sinatzeak esan nahi du pertsona horri fidagarritasuna ematen diozula. Gako bat sinatu baino lehenago, egiaztatu gakoaren hatz-markak seguruak direla eta gakoa benetan pertsona horrena dela.