This is the 17703rd most frequent Polish word.
zmęczona
"Zmęczona" means "tired" (feminine form).
The word 'zmęczona' is the feminine form of the adjective 'tired', used to describe the state of the person speaking.
Jestem zmęczona po całym dniu pracy.
I am tired after an entire day of work.
Here, 'zmęczoną' is the accusative singular feminine form, describing the direct object of the sentence.
Ona wygląda na zmęczoną po biegu.
She looks tired after the run.
In this case, 'zmęczone' is the plural feminine form, describing the state of the group speaking.