。
She scolded the child for interrupting the conversation.
Literal
She [topic-は] child [subject-が] conversation [target-に] cut-in [nominalizer-の] [object-を] scolded.
割り込む ('cut in, interrupt, force one's way into') is a compound verb of 割る ('split, divide') + 込む ('into'), painting a vivid image of pushing one's way into something already in progress. Used for cutting in line (列に割り込む), interrupting conversation (話に割り込む), or forcing one's way through a crowd. しかる ('to scold') is one of the workhorse verbs of parental discipline, alongside 怒る ('get angry'), 叱責する ('reprimand'), and 注意する ('caution, warn'). The cultural norm against 人の話に割り込む runs deep in Japanese conversational etiquette.