What is the meaning of this document T2.nii_Cohen_f2?

After completing the two-sample t-test by SA, two files were generated:T2& T2.nii_Cohen_f2.

What is the meaning of this document T2.nii_Cohen_f2?

Cohen_f2 is the effect size map. See https://en.wikipedia.org/wiki/Effect_size Cohen's f square