First, arrange the numbers from least to greatest. Remember that with negative numbers, larger numbers like -7 (if you ignore the minus sign) are less than smaller numbers.

-7 -6 -6 -5 -5 -5 -4 -4

Now count how many times each number appears.

-7 appears 1 time.
-6 appears 2 times.
-5 appears 3 times.
-4 appears 2 times.

The number that appears most often is -5.
Hence, The mode is -5.