Questions & Answers about La faïence est fragile.
Because French often uses the definite article (le / la / les) to talk about something in general.
So La faïence est fragile means something like earthenware is fragile or faience is fragile as a general statement.
If you said Une faïence est fragile, it would sound odd in most contexts, because faïence is usually being treated here as a material or category, not as one single unspecified item.