With these numbers I have to find the median. Please help mee!!

Write them in order from least to greatest,
11.9, 12.0, 12.3, 12.4, 12.4, 12.5, 12.7,12.8, 12.9, 13.1, 13.2, 13.8
then eliminate one from each side until you find the middle one,
12.5, 12.7
you have two middle, so you find the middle number in between them.

12.6 is the median.