The first cell shows 'A', so type the name of a country that begins with A. This will reveal the hint for the next answer: the hint will be either the 1st letter, the 2nd letter (shown for example as _a) or the 3rd letter (shown for example as _ _a)
After the 1st column it seems to be messed up. I typed in a bunch of countries with a as the second letter, none of which were accepted. Then I typed in Brazil (as a random guess) and it was accepted, which doesn't in any way fit the pattern.
_ _ a