What it means
Means looking sharp and new, especially when your fit’s clean and your trainers are spotless, like you’ve just peeled the tags off. You’ll hear it as a quick compliment, you look fresh. It also has a second edge: don’t get fresh with me means don’t get cheeky, mouthy, or start giving backchat.
Usage examples
"He rolls into the pub in box-fresh Air Max and a crisp tracksuit, so everyone’s saying he looks fresh, till he chats back and gets told off."
"New trainers, sharp jacket, you're looking proper fresh today."
"Don't get fresh with me, young man, just answer the question."
"You can't turn up in a white tee that crisp and crep protect still shining and not expect people to say you're fresh."
"Oi, don't get fresh with your nan, just grab the shopping and quit the little attitude routine."
Where it comes from
The style compliment is the old plain-English fresh, meaning new, clean, lively, not long out of the box. The cheeky sense is older too. In US and British English, get fresh was already used for being impudent, and that usage is widely linked to German frech, meaning bold or insolent.