Because 1 is not prime, there are 0 prime dates in January.

2 is prime, so the prime dates in February are 2/2, 2/3, 2/5, 2/7, 2/11, 2/13, 2/17, 2/19, and 2/23 for a total of 8

3 is prime, so there are 10 prime dates in March.

4 is not prime, 0 April Prime dates

5 is prime, 10 prime dates in May

6 is not prime, 0 June prime dates

7 is prime, 10 July prime dates

8 is not prime, 0 August prime Dates

9 is not prime, 0 September prime dates

10 is not prime, 0 October prime dates

11 is prime, 9 November prime dates

12 is not prime, 0 December prime dates.

Together, there are 1+8+10+0+10+0+10+0+0+0+9+0 = 48 prime dates in 2020, 49 on a leap year (2/29 on Febuary)