Explanation:
remember, a probability is always desired cases over possible cases.
and the combination of the probabilities of two (or more) events means to multiply these probabilities.
the probability to get a specific number on the spinner is 1/4 (1 desired number over 4 possible numbers).
so, to get first a number less than 3 ... - that means, the only desired outcome is the number 2.
so,
1/4
to get 5 on the second spin ?
again,
1/4
the combination of both events into one delivers the probability of
1/4 × 1/4 = 1/16