。
She is kind.
Literal
[topic-は] kind.
A bare-bones characterization: topic + i-adjective predicate. やさしい spans 'kind, gentle, considerate, easy(-to-handle)' depending on context — applied to people it means kind/gentle, applied to a problem it means 'easy.' The casual short form (no copula needed for an i-adjective) and minimal structure make this a textbook example of the most basic adjectival predicate in Japanese.