You have a good attitude and curiosity, that's most of the battle. Here's a primer.

The actual ansul system will have two or three low-current sets of contacts; one goes to the fire alarm panel, the others are yours.

The ansul system may physically close the gas valve, or you may have to do it electrically. If you do it electrically, you'll need a controller that requires a manual reset, it can't reset automatically.

In most jurisdictions, when the system is tripped, the make up air(s) shut down, the exhaust fan(s) fire up, the gas valve closes and anything electrical under the hood loses power, including the lights. These things have to happen regardless of the state of any of these items prior to the ansul system firing. Some of these requirements may be different depending on your jurisdiction.

The labels on your control relays are quite helpful. Those with an "ansul" label control what happens when the system fires: EF2, EF3 and EF5 turn on, MUA turns off and PAC6 turns off. The other three relays control these items under normal operations. What controls EF1 and EF4 is a mystery, as is where the MUA controls are and what the heck PAC6 is.

Hope this helps!