。
That'll be 30 euros.
Literal
30 euros [into-に] become.
The fixed transaction phrase [price]になります — a staple of Japanese customer service at cash registers. The にする/になる pattern treats the total as something the situation 'becomes,' a politely distanced way of presenting a figure. The verb in ます-form keeps the register polite. ユーロ is the loanword for 'euro.' This is the exact phrase you'd hear at any retailer in Japan (replace the amount and currency).