how to show the size of a file in linux code example

Example 1: list file size as mb

ls -l --block-size=M

Example 2: ls human readable size

ls -l filename   #Displays Size of the specified file
ls -l *          #Displays Size of All the files in the current directory
ls -al *         #Displays Size of All the files including hidden files in the current directory
ls -al dir/      #Displays Size of All the files including hidden files in the 'dir' directory