This is the 27th most frequent Greek word.
μία
"Μία" means "one" (feminine form) in English.
'Μία' is used here to mean 'one' as in 'one time' or 'once.'
Μία φορά πήγα στο μουσείο.
Once I visited the museum.
'Μία' is used here as the feminine form of 'one' in agreement with the feminine noun 'σοκολάτα.'
Θέλω μία σοκολάτα, παρακαλώ.
I would like one chocolate, please.
'Μία' is used here to indicate 'a' or 'one' solution, emphasizing the singularity of it.