It could mean either, and the meaning would depend on the context. Referring to your girlfriend as 'my girl' is very old-fashioned - it sounds like something from the 1950s. While we do still use the term 'girlfriend' for grown women in a relationship context, nowadays it sounds odd and rather patronising to actually refer to a female partner as anybody's 'girl'. You might hear 'my girl' in a song, but most people would not say this. It's possible to refer to your daughter as your 'girl', especially if you only have one daughter. For example, it would be normal to say this: "We've got three kids. My wife's taking our two boys shopping to buy their school uniforms this morning, and I'm taking our girl to play in the park." In these cases, the context would make it obvious that you're talking about your child. As for the phrase 'going out', this can mean going on a date (or being in a relationship) with someone. It can also have the more literal meaning of heading out to somewhere outside your home. If your meaning is the first one, you should say "I'm going out with my girlfriend" (not 'girl') to avoid sounding old-fashioned and patronising. I hope that helps.

Girlfriend.

اَی توو روحت مهرداد از بس توی فکر جی اف و دادر و اینایی تِر زدی به انگلیسی یاد گرفتنت. برو از خدا شرم کن داداش