If you don't want to install anything you always open new Finder window, select List Viev, (cmd-2) then (cmd-j) and enable Calculate All Sizes option at the bottom. If you like it you can enable it by pressing Use as Defaults. Remeber that it will only calculate sizes of visible folders.
To fully visualise what's eating HDD space you can use the following:
GrandPerspective http://grandperspectiv.sourceforge.net/
OmniDiskSweeper https://www.omnigroup.com/more
Disk Inventory X http://www.derlien.com/
All are free, allow you to trash selected files etc, differences are cosmetic.
You can find a lot of stuff in Library/Application Support etc like full Garageband libraries etc.
IMHO removing languages is last resort.
