。
She left for London yesterday.
Literal
She [topic-は] yesterday London [toward-へ] departed.
ロンドン is the standard katakana rendering of London — Japanese maps the final 'n' to ン (the only coda consonant the language allows) and inserts a vowel after every other consonant, since most Japanese syllables follow a strict consonant-vowel pattern. Place names get this treatment uniformly: ニューヨーク, パリ, ベルリン, モスクワ. 出発する pairs the Sino-Japanese noun 出発 ('departure') with する; the bare verbs 発つ and 立つ are more literary alternatives.