。
She likes short skirts.
Literal
She [topic-は] short skirt [subject-が] is-liked.
A textbook example of the が-marked-object pattern with 好き. 好き ('liked') is a na-adjective that grammatically marks its target with が, not を — the target is the subject of the stative predicate, not the object of an action. 短い is a regular i-adjective ('short') in attributive position. スカート is a katakana loanword from English 'skirt.'