。
She can skate.
Literal
She [topic-は] skating [subject-が] can-do.
~ができる is the noun-attaching potential pattern: noun + が + できる ('can do X'). The noun スケート ('skating') becomes the grammatical subject of できる, which is itself the potential of する. The mirror pattern with verbs is verb-stem + ことができる (スケートをすることができる, 'be able to do skating'). Both work; the noun pattern is shorter and more idiomatic when the noun naturally describes an activity (skating, swimming, languages, sports).