These mean the tippable objects. (Lamp posts, signs, trees...) The objects in your track won't react to ramming at all if you don't write their textfiles here.
If you have a lamp post in your track (&02Lamp.ACT), you would write 02Lamp.txt here. (Without the "&")
And the 02Lamp.txt must be in "data/noncars"-folder: There are all the textfiles. (Which contain the physics of the objects)
Now, you (probably) have two or more of these lamp posts in your track. However, write each textfile only once, even if you had hundreds of lamp posts in your track.
// Non CarObjects
5 // Number of noncar textfiles.