:setlocal spell spelllang=pl
Cannot find spell file for "pl" in latin1
Do you want me to try downloading it?

Downloading pl.latin1.spl...
:!curl -o '/tmp/v139537/0.spl' 'http://ftp.vim.org/pub/vim/runtime/spell/pl.latin1.spl'
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
"/tmp/v139537/0.spl" 9L, 309C
Could not find it, trying pl.ascii.spl...
:!curl -o '/tmp/v139537/0.spl' 'http://ftp.vim.org/pub/vim/runtime/spell/pl.ascii.spl'
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
"/tmp/v139537/0.spl" [readonly] 9L, 308C
Sorry, downloading failed
Warning: Cannot find word list "pl.latin1.spl" or "pl.ascii.spl"
Press ENTER or type command to continue