Can i use this on fence to keep birds from eating?

You can use this almost everywhere. I placed a small bead on the top edge of a plaque next to a POW/MIA chair and it works great. The birds do not like the sticky stuff on their feet and haven't landed on it since. Hope this helps.

how does this product work?

A couple of ways. For most animals, the fact that it's a sticky glue like product is all that's needed to chase them away. But it also contains polybutene which is irritable to most any animal if they "linger" on it. So if the gluey feel of the gel (or liquid) doesn't chase them away, the polybutene will.Hope this helps!Jonathan,Customer CareU-Spray Bugspray

Is there a bird begone spray?

No you need a caulking gun to apply it.

will this help bird from making a nest in my dryer vent and help keep raccoon out of my yard

This is a product with a gooey consistency that is for spreading on surfaces with a caulking gun where birds land. Apparently the birds don't like the sticky feeling or maybe it smells bad to them. So, it might help keep them out of your dryer vent. I would guess that it will do nothing for keeping a raccoon out of your yard. I don't even know how you would begin to use it for that. I used this product to keep woodpeckers from pecking holes in my wood trim boards.