Pick a directory you want to analyze and run ncdu . Yes, with the dot. It should look like that:

If you don’t have ncdu installed, install it.
If you can’t, you can use the simpler standard utility du like that: du -hs *
-h makes the output humanly readable, -s tells du that you want to see the total size of items without listing every directory in the file system tree, and * says that you want du to operate on all of the items in the current directory.

The output will be something like:
xxM some_directory
xxM some_file
xxG another_directory

Repeat if necessary for sub-directories.