The spinner has sectors labeled with the odd numbers $1, 3, 5, 7, 9$ (the shaded sectors). There are $5$ shaded sectors in total.

Among these, find which are multiples of $3$:

$3 = 3 \times 1 \; \checkmark$ $9 = 3 \times 3 \; \checkmark$

The numbers $1$, $5$, and $7$ are not multiples of $3$.

So $2$ out of $5$ shaded sectors are multiples of $3$:

$P(\text{multiple of 3} \mid \text{shaded}) = \frac{2}{5}$