The subshell is identified by the azimuthal quantum number ($l$).

1. Identify Subshell: For $l = 1$, the subshell is a p-subshell. Since $n=3$, it is specifically the $3p$ subshell.
2. Determine Capacity: The maximum number of electrons in a subshell is determined by the formula $2(2l + 1)$. Substitute $l = 1$: $2(2(1) + 1) = 2(3) = 6$ electrons. Alternatively, a p-subshell contains 3 orbitals ($p_x, p_y, p_z$). According to the Pauli Exclusion Principle, each orbital holds 2 electrons. Total = $3 \times 2 = 6$.