The only free and comprehensive online etymological dictionary of the Spanish language
tabla f. (Noun) "plank;" "slab"
12th cent. From Vulgar Latin tabla 'id.' From Latin tabula "board." From Proto-Italic *taflā- 'id.' Of uncertain origin.
Indo-European
Romance
Portuguese talião, Italian taglione

In the 3rd or 4th cent. text Appendix Probi we find the line: tabula non tabla "[the word for 'board' is] tabula, not tabla." The author's spelling correction proves how the word was pronounced by common speakers, and offers a rare glimpse of the evolution of Latin into Romance languages such as Spanish.