。
She's very personable.
Literal
She [topic-は] manner-with-people [subject-が] good.
人当たり (ひとあたり) refers to one's manner or bearing when dealing with others. Combined with がいい, it describes someone who comes across well — approachable, pleasant, easy to be around. This follows a productive Japanese pattern where [abstract quality]がいい/が悪い describes personal traits: 人当たりがいい ('personable'), 愛想がいい ('friendly'), 感じがいい ('gives a good impression').