"I am a girl."
Yes. These are Instrumental forms of "dziewczynka" and "dziewczyna". Generally, "dziewczyna" is an older girl. However, there is no clear border. It can start at the age of a teenager, but you could also call an 8-year old like that, that's a matter of one's opinion.
"dziewczyna", if you use some possessive in front of it, means "girlfriend".
"a" is NOT pronounced like the "a" in the English word "walk". "A" in "walk" is pronounced like the Polish "O" letter. Polish "a" is just a normal "ah" sound, similar to "a" in "large" or "father". As for the "ą" letter, it has several different pronunciations depending on what sound comes after it. It could be the nasal /ɔ̃/ sound, the standard /ɔ/ sound, or it could be pronounced as [ɔn], [ɔŋ] or [ɔm]. For example, "ząb" is pronounced as /zomp/. The same is true about "ę", only with the /ɛ/ sound instead of /ɔ/.
I: Little Dee goes to the ZOO, she is INTERESTED in ELEPHANTS & squeezes through the bars & WANDERS far into the CAGE experiencing the other wonders inside the ZOO.
She is so YOUNG & NEVEROUS about her ĄDVENTURE. But proceeds as she is a curious DZIEWCZYNĄ. Maybe she was inspired by Dora the explorer.
II: GO HOME DZIEWCZYNĄ before the GNOMES ascend at night. XD
II: Ona jest dziewczynką
JEST EM D ZI EW C ZY NĄ. ~
DZIEW CZYN Ą
♫ JIV CHIN NOM = Ą
nominative dziewczyna /dziewczyny (PL)
genitive: dziewczyny /dziewczyn (PL)
dative: dziewczynie / dziewczynom (PL)
accusative: dziewczynę /dziewczyny (PL)
instrumental: dziewczyną /dziewczynami (PL)
locative: dziewczynie /dziewczynach (PL)
vocative: dziewczyno /dziewczyny (PL)