An atomic orbital is uniquely defined by a set of three quantum numbers: the principal quantum number ($n$), the azimuthal quantum number ($l$), and the magnetic quantum number ($m_l$).

1. Principal Quantum Number ($n = 3$): Indicates the electrons are in the third principal shell.
2. Azimuthal Quantum Number ($l = 2$): Corresponds to the $d$ subshell. Thus, the electron is in the $3d$ subshell.
3. Magnetic Quantum Number ($m = +2$): Describes the spatial orientation of the orbital. For $l = 2$, the possible values of $m_l$ are $-2, -1, 0, +1, +2$, corresponding to the five $d$ orbitals. The specific value $m = +2$ identifies exactly one specific orbital among them.

Therefore, the set of quantum numbers ($n=3, l=2, m=+2$) refers to a single orbital.