。
She sat down at the piano and started to play.
Literal
She [topic-は] piano [of-の] front [at-に] sat [and-て] play-started.
ピアノの前に ('at the front of the piano, in front of the piano') uses the relational noun 前 with の and に to anchor the location. Japanese prefers these relational-noun constructions (~の前/後ろ/上/下/中/外) over single-word prepositions, building up locations from a noun + relational + particle. ひきはじめた ('started playing') chains the verb stem of ひく to はじめる, an instance of the productive verb-stem + 始める pattern that turns any action verb into 'start V-ing.' The te-form 座って sequences the actions cleanly: sit, then play.