。
She pushed the door open.
Literal
She [topic-は] that door [object-を] push-opened.
押し開ける is a compound verb pairing 押す ('push') with 開ける ('open'), giving 'push open' as a single fluid action. Compound verbs of this manner-plus-result pattern are everywhere in Japanese: 引き上げる ('pull up'), 切り倒す ('cut down'), 飛び越える ('jump over'). They tighten what English would express with two separate verbs into a single lexicalized motion. Japanese is rich in these productive compounds, so much so that fluent learners often note that picking up the patterns of compound verb formation is a key step in moving from intermediate to advanced.