save would be found under MATLAB_ROOT\toolbox\matlab\general\save.m.
But as the warning said, you have another save.m under your work folder and it occurs name conflict.
Please rename the save.m under "C:\Users\35191\OneDrive - Universidade de
Aveiro\Emotional transition - recognition\MATLAB -
functions" to another file name such as mysave.m, and the issue will be resolved.