The term "iron" refers to a classic type of metal jig used in Southern California for the last half-century. They are not commonly sold in this area.
The jigs are made of various aluminum alloys, some light for surface retrieves, some heavy for yo-yo'ing deep. Commonly they are 4 to 8 inches long, usually painted, sometimes chromed. Common colors are blue/white, green/yellow, mackeral pattern, scrambled egg, wounded soldier (olive green with a red spot) and sardine.
Leading brands were/are Salas, Tady, Hacker, Sumo and Straggler. These days Salas and Tady are probably the leaders. Hacker and Straggler died off I believe. Do a search for Salas jigs to see some pics.
There is a whole class of "jig sticks" used for throwing the iron. Jig rods are generally 8 feet long with a slower taper than live-bait rods (Calstar 800M is a good example of a jig stick). Jig rods are designed for casting, but are admittedly poor for fighting fish. Jig reels have high-speed retrieve. The classic Penn Jigmaster (4:1) has been largely replaced by Newells and other 5 or 6:1 reels. Spinning reels are not credible jig reels. Line is 30 or 40 pound mono.
A good caster can hurl a jig the better part of 100 yards with pinpoint accuracy. This comes in handy when casting to kelp paddies and breaking fish. Jig fishing is a specialty, and a deadly one at that.