。
She told him to please sit down.
Literal
She [topic-は] him [to-に] please-sit [quotative-と] said.
A direct quotation preserved by と言う — '(she) said "please sit down".' The inner clause uses ~てください, the polite imperative. Compare with the reported version 座るように言った — that would lose the verbatim politeness marker. Quotative と vs. ように with reporting verbs gives a choice between direct quotation (verbatim) and indirect report (paraphrased).