Your code opens a folder given in database and in that folder saves two .mat files with name Subtrain.mat and trainID.mat. In these files, the data is provided by variables Subtrain and trainID respectively.
clc; clear all ;
database = 'Folder' ;
Subtrain = rand(100,1) ;
trainID = 'This can be number or string' ;
mkdir(database) % will make new folder
x= strcat(database,'/Subtrain'); %horizontally concatenatesstrings in arrays
save(x,'Subtrain') % saves variable
y = strcat(database,'/trainID');
save(y,'trainID')
