When Peter, freed from prison, knocked at the gate, what did the servant girl who answered do?

Answer: Ran inside without opening it

Rhoda recognized Peter's voice and was so overjoyed she forgot to open the gate; she ran in to announce him while he kept knocking.

“When she recognized Peter’s voice, she was so overjoyed that she forgot to open the gate, but ran inside and announced, “Peter is standing at the gate!””— Acts 12:14 (BSB)