size (a) = b % this will return the size of array (a) in terms of Number of rows and columns and assign in to array (b). therefore b(1,1)= number of rows of (a) and b (1,2) is the number of columns of (a)
save ('abcd') % this will save the current workspace under abcd.mat filename. this function is not particularly helfull when you are a beginner but when you will have to write scripts and you will have to clear workspaces within the script and call it back to do another function the it will dawn upon you why you have save. For now you can simply go to the save button in the workspace window and save the workspace if you wish
disp (a) % displays the elements of array (a)