WELSH-L is for discussion in the Welsh language (or in the related languages Breton and Cornish). It is not intended as a place for general discussion in English (though postings in English are acceptable if they closely concern the Welsh language).
Further information is available on the WELSH-L website.
See also the related (non-Listserv) list CYMRAEG-L, for learners of the Welsh language (especially beginners). CYMRAEG-L has postings in both English and Welsh (with glossary or translation).
For general discussion in English of things closely or marginally related to Wales (including genealogy) a good place to start is the newsgroup soc.culture.welsh - or possibly the CELTIC-L list: see its website.