Actually, that would be incorrect. "Table" in this sentence is indefinite (theres not a definite article "al/il" in front of it). Saying "This table" would be making the table definite. Therefore, it must be "this is a French table" since both words are indefinite. If we said "haadhahi (il)Taawila fransiia" that would translate as "This table is French". Good question!