Noun: unknown soldier.
Tuntematon is an adjective that means ”unknown.” It is constructed from tuntea, a verb meaning ”to feel,” ”to sense” or ”to know” + ma (front vowel harmony variant –mä), a deverbal suffix which is used to form result nouns from verbs + -ton (front vowel harmony variant -tön) a suffix indicating a lack of something. Tuntematon is also the negative 3rd participle of tuntea. (See tuntea fully conjugated here.)
Sotilas means soldier. In chess, it can also mean a pawn. As a modifier in compound terms it can also mean ”military.”
The film is about the Continuation War between Finland and the Soviet Union from the point of view of the soldiers. The 1955 version is incredibly well-known and is broadcast every Independence Day (December 6th) in Finland on YLE, national television.