What is the Brachah that she requested?
Rashi (Yehoshua 15:19): It is income.
Radak (Yehoshua 15:19, citing Targum Yonasan): It is inheritance.
What was her complaint "you gave to me Eretz ha'Negev"?
Rashi (from Temurah 16a): It is a man without any [monetary] good, only Torah.
Refer to Yehoshua 15:19:2:1.
How did Kalev answer her?
Rashi: He gave to her Beis ha'Ba'al (a field that need not be irrigated; the rain suffices for it).
Rashi (Yehoshua 15:15): He gave to her springs.
Radak (Yehoshua 15:15): He gave to her pools of gathered water.
Malbim (11): He gave to her springs to irrigate her dry land, and hinted to her that she already has a husband who draws running water from the Supreme source of Brachah, and below (lower) Divine and human Chachmah.