The Lezoux plate is a ceramic plate discovered in 1970 at Lezoux (Puy-de-Dôme), which contains one of the longer texts in the Gaulish language (in a Gallo-Latin cursive script) which has yet been found.
Since it is fragmentary, only parts of the text can be read, and only a fragment of that can be reliably translated.
From those bits, it seems to be a list of aphorisms directed toward a young man.
[1] The last form, -breto is likely related to Old Irish bráth "judgement" but the vowel is unexpected.
[2]