What size do you take?
'Taglia' is 'TAL-ya' — the 'gli' combination makes a palatal 'ly' sound, like the 'll' in 'million'.
Said by staff to help find the right size. You'll hear this constantly in Italian shops. Know your European size before you go.
'Porta' here means 'do you wear/carry', from 'portare'. In Italian, you 'carry' a size rather than 'being' a size. Formal pronoun Lei is implied.
Che numero porta? (shoes)
What shoe size do you take?
Use 'numero' for shoes, 'taglia' for clothing
Conosce la sua taglia?
Do you know your size?
Asked when customer seems unsure
Di solito che taglia mette?
What size do you usually wear?
More conversational, informal shops
Italian clothing sizes follow the European system. Women's sizes typically run 36–52, men's 44–58. Sizes can vary significantly between brands, so always try before buying.