This is the 8757th most frequent Russian word.
пленный
Prisoner.
The word 'пленный' here is used as an adjective to describe the soldier, meaning 'captured, in captivity'.
Пленный солдат был освобожден после переговоров.
The captured soldier was released after negotiations.
In this sentence, 'пленный' is used as a noun meaning 'a captive' to describe someone feeling imprisoned.
Рыцарь чувствовал себя как пленный в замке врага.
The knight felt like a captive in the enemy's castle.
Here, 'пленена' is a verb derived from 'пленный,' used in a figurative sense to mean 'captivated' or 'charmed'.