"Language" - extended English name of the language and corresponding ISO code

“Unknown words” - is the number of unique words not found in the dictionary of a particular language. “-” , which means that the spellchecker is not configured to check translations for this language (usually because an aspell dictionary for the language is not available)

“Messages” - contains all the strings for lang extracted from the po files: you can use any spellchecker against this file to look for typos. This file is very useful also when improving consistency: when translations are spread over many po files, it is difficult to make sure that certain rules are applied to all files, so here you can check for example that "CD-ROM" is written always the same way.

“List of unknown words” - is a sorted list of words not found in the aspell dictionary along with the number of occurrences.

“suspect variables” - po files often contain variables ${LIKE_THIS}; a script checks that the name of the variable in the msgid is matched in the msgstr. It is also checked that the number of variables in the msgstr is the same in the msgid.

“custom wordlist” - translators can write a list of custom words not found in the aspell dictionary for their language. More details about wordlists can be found here (FIXME).

“all files” - is a tarball containing all the above files. Translators can download it and work off-line.