# the cave of Machpelah

"the cave in Machpela." Machpela was the name of an area or region. Ephron owned a field in Machpela and the cave that was in the field. 

# which is at the end of his field

This also tells something about the cave. The cave was at the end of Ephron's field.

# sell it to me publicly

"sell it to me in front of you all" or "sell it to me in your presence"

# as a property

"as a piece of land that I may own and use"