For the size of a file:
ls -lh somefile.txt | awk '{ print $5}'
For the size of a directory:
du -sh /somedirectory
For the size of your home directory:
du -sh /pathtoyourdirectory
Because the last command might delay to extract the output, in their home directory there is a file, named quota.txt, by which users can be aware of their storage size (along with their quota limits)