1) One is liable for damages caused by fire only if the burned objects were exposed, not hidden. 2) One is liable for anything standing upright burned by the fire, including trees and animals. 3) The passage discusses why the Torah listed specific items like "standing grain" - to indicate liability even for burning the ground itself of a field.

1. Gemara Notes p. 48 דף ס עמוד א

2. One is only חייב for something that is exposed, but not something hidden One is חייב for anything that stands upright, including trees and animals One is חייב for anything that stands upright, including trees and animals One is חייב even if his fire burned only one of the objects listed One is חייב even if his fire burned only one of the objects listed Since it says “or” by the standing grain, it also says “or” by the field רבנן ר ' יהודה

3. Why does the Passuk need to teach the word “field”? To include that one is חייב to pay for the earth and stones that were singed So why didn’t the Torah just write “the field”, and not write the other three? If the Torah had only written “the field”, I would have said he is only חייב for what is in the field, but not the ground itself. Therefore the Torah taught “the standing grain” as well to teach us that “the field” refers to the ground itself. הוה אמינא

4. Gemara Notes 47 - 50 דף ס עמוד א

5. One is חייב for even the burnt soil and stones השדה רבנן – One is פטור for things that are hidden ר ' יהודה – One is also חייב for trees and animals הקמה One is חייב because we don’t assume its an אונס One is not חייב for something worth so much, because it must have been an אונס גדיש One is חייב for things that have such little value One is not חייב for things that have such little value קוצים קא משמע לן (What it teaches us) הוה אמינא (What I would have thought without it)