we can always do a prime factoring of it, and check
50 = 2*5*5
2*5²
a perfect square, so-called, is the resulting number of a squared value, well 50 is not the result of anything squared, is the result of 3 factors, in this case 2,5 and 5.
a perfect square will be something like say 64, or 144, because
64 = 8*8
8²
144 = 12*12
12²