That device is a Solid State Relay ( SSR ). It uses a TRIAC or two thyristors to switch a load ( typically AC mains ). It is similar to a relay, with the advantage of faster switching and no moving parts. A small voltage ( from 3 volts DC ) is applied to the control terminals to turn it on. It turns off as soon as that control is removed. This means it is non-latching. The relay required here, the JQX-29F-A , is a latching type, so this SSR will not do the job.
Another thread on the same topic ( JQX-29F relay ) has been updated with a link to a suitable replacement relay at a reasonable price, sourced from AliExpress:
hi i was selding today with a rockworth ar 120 mig welder when the feed just stopped then i pull triger i can here it clicking inside i checked the feed moter with a 9v battery and it moving i check the 2 fuses on the pcb there ok can anyone help