Sorry for the delay I was away for a bit!

Maria is asking him to speculate on why she hasn't made any attempt to fight back, which might seem strange considering she is claiming to be a soldier.

The Scouts are a specific part of the military of the country of Arcartus (the blue one on the right side of the map). Arcartus and the Scouts have been tangentially involved in the plot since a woman named Lexine Tristan was killed a little over a day ago in-game time and papers were found on her body implicating a few officers from their ranks, which is why the Arcartis are currently interested in investigating that rumor. The Scouts themselves are of moderate renown, although only among circles interested in a foreign country's military. Their presence in Keilaudrin is unwelcome, because of a reputation as infiltrators, saboteurs, and generally dishonorable wet-workers. The military of Arcartus is split between the jurisdiction of the State and the Royal Family, with the royal family granted largely ceremonial authority over a select few groups when the state military is not already using them, which is where they get their naming convention.

The Keilaud military is more feudal in its organization so it's difficult to provide a comparison and none of them have come up in the thread other than the differences between the palace guard and the king's knights (The Order of the Thistle), but in tl;dr the scouts are something akin to special forces.