What does the number of orbitals in a subshell represent?
Short answer

Number of orbitals does not have direct relation to either probability of  electrons occupying them, either the space they are describing.

The related probabibility is to be understood as:

IF the electron is in the quantum state, belonging to the particular orbital, THEN the wave function of the orbital describes spatial distribution of the electron  occurence probability, what is geometrically illustrated by the orbital 3D shape.

Longer answer
There are 3 meanings of the term orbital:


A complex wave function $\Psi$ being a particular solution of the quantum wave equation
A quantum state of an electron, following 1., described by particular quantum numbers $n$, $l$ and $m$, representing discrete values of electron energy, orbital angular momentum and one of component of angular momentum, respectively.
3D shape, following 1. and 2., representing statistical  probability of the electron presence at given point by$\Psi^2$, determined by the conventional value by residual external probability and by the isoprobability surface. 


If there is 1 orbital 2s and 3 orbitals 2p, it means,
for  $n=2$  and $l=0$, there is 1 value $m=0$.
But for $n=2$  and $l=1$,
there are 3 values $m=-1,0,+1$

Electrons are fermions with half integer 4th spin quantum number $m_s$, and every electron in the atom must have unique set of quantum numbers.

Therefore there can be 2 electrons in the orbital 2s, having $n=2$, $l=0$.

But there can be up to 6 electrons in 3 2p orbitals, having $n=2$, $l=1$.