In the electron configuration notation, the "3s" indicates the electron shell and subshell. The number before the subshell letter represents the principal quantum number (n), which determines the energy level of the electron. The letter after the number represents the type of subshell, and "s" corresponds to the spherical-shaped s subshell.
The s subshell can hold a maximum of 2 electrons. According to the Aufbau principle, electrons fill the lowest energy levels first before moving to higher levels. In the 3s subshell, there is only one s orbital, so it can accommodate a maximum of 2 electrons.
Therefore, there is 1 s orbital in the 3s shell.