What does a Sabbath day's journey mean in Acts 1:12?

In Acts 1:12, Luke writes: "Then returned they unto Jerusalem from the mount called Olivet, which is from Jerusalem a sabbath day's journey" (Acts 1:12). A reader naturally wonders: why is it described specifically as a "Sabbath day's journey," and what is the purpose of this detail? Is it referring to some special command from God regarding the number of steps allowed on the Sabbath? To understand this text correctly, it is essential to look at both the historical and spiritual context. Here, Luke is not introducing a new commandment, but rather using an expression familiar to the Jewish people to indicate a very short distance.