Shield Generator is the 36th level in Serious Sam 2.
Serious Sam goes down the tower he entered in the previous level. After clearing it out of all resistance, he enters a few grassy, park-like areas filled with enemies. When he's done with the park areas, he finds a path that leads to a large area filled with garages and two cranes, presumably a warehouse. However, the area has been co-opted by Mental into being a huge area where his forces constantly come out of the garages. As expected, Sam manages to clear out all of the garages of enemies.
On the opposite side of the warehouse area, Sam finds a trolly. He boards it and rides it to the Shield Generator. After wiping out some enemies, he enters it, but is caught in a trap before he can shut down the generator.
1. In the first grassy field past the sloped walkway, there is a strange machine and a dead bunny near the back wall. You'll need to stack some crates so that you can you can toss the bunny in the rectangular opening and reach the Serious Bomb on the device. These crates can be found on the upper right corner. Once the bunny has been put in the machine, a secret will register and a ragdoll bunny sausage will come out of the machine, which you can mess around with.
Not a Secret, but still helpful. In the part of the level where enemies come out of garages, go near the crates in the first portion of the area (or where they were if they've already been destroyed). Turn left, and you'll see a device with a red switch on top of it. Walk over to it and use it. A nearby crane will move and drop a Serious Damage right next to you.
2. Past the crates, you will be in a huge arena with garages on your right. Look left until you see another machine sticking up with a red switch on it. Walk over to it and use it. Another crane will move and drop off both an Extra Large Armor and a Super Health. Pressing the switch will register the secret.