IPA: /ˈbɛkənər/
KK: /ˈbɛkənər/
A person who signals or calls someone over, often using hand gestures or other signs.
The beckoner waved his hand to get the attention of the passerby.
Beckoner → It is formed from "beckon" (from Old English *beacnian*, meaning to signal or summon) and the suffix "-er" (meaning a person who). A beckoner is a person who signals or summons someone.
Think of someone who is 'signaling' ('beckon') to another person — the '-er' indicates that this is a person doing the signaling.