The backer poker term refers to a person financially supporting a poker player. Backers are a common aspect of the poker world and even support many of the world-famous poker pros.
In a sense, backers are investors that put money into poker players hoping for a profit on their backing.
For example, there’s a player with extensive poker skills but currently going through bankroll problems. The baker approaches the player offering to buy them into a WSOP event. In return, the player agrees that they’ll share any profits 70/30 in the backer’s favor.