para decirle que llegaría tarde

to tell him/her that [someone] would be late

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phrase Rare #39,068
to tell him/her that [someone] would be late Le means “to him,” “to her,” or “to you” in a formal context; the person referred to is usually clear from context. The subject of llegaría is also understood from context.
SP: Llamé a mi jefe para decirle que llegaría tarde.
EN: I called my boss to tell him that I would be late.

Ella lo llamó para decirle que llegaría tarde.

She called him to tell him she would be late.

Ella le llamó para decirle que llegaría tarde.

She called him to tell him she would be late.

Él llamó a Mary para decirle que llegaría tarde.

He called Mary to tell her he would be late.

Jane llamó a Mary para decirle que llegaría tarde.

Jane called Mary to tell her she would be late.

Tom llamó a María para decirle que llegaría tarde.

Tom called María to tell her he would be late.

Tom llamó a Mary para decirle que llegaría tarde.

Tom called Mary to tell her he would be late.