This numeric value is used as a "spacer" between individual rows of the emulator frame. When using the "Browser" EntryStyle, the surrounding borders of entry fields create the need for additional space between rows.
By altering this setting, you can select the best balance of screen height (and font size) and the potential for entry field borders to overlap vertically.
The default is 3 pixels, but any numeric value is acceptable (avoid large numbers!).
For VT/ANSI and other character mode protocols that may employ box drawing characters, this should be set to 0 to ensure no vertical gaps appear in the left and right borders of the "box".
