。
She was careful not to break the glass.
Literal
She [topic-は] cup [object-を] not-break [so-as-not-to-ように] paid-attention.
Two pieces. 気をつける ('to be careful, pay attention,' literally 'attach one's spirit') is one of the body-of-mind idioms central to Japanese — 気 functions as 'spirit, attention, mind.' Pairing it with ~ないように ('so as not to') makes the construction 'be careful not to do X.' コップ ('drinking glass, tumbler') is a Dutch/Portuguese loanword from kop / copo — both candidates, with the Dutch route most commonly cited given Japan's long Edo-period trade with the Dutch through Dejima in Nagasaki, where many household-item words entered Japanese.