Corporate names and logos are often symbols. For example, there is no logical connection between the game of dominos and pizza. Thus, the name and logos for "Dominos Pizza" are symbols.
The same is true of such corporate names and logos as: "Exxon," "Microsoft," "American Express," "NASA," and so on.
The English alphabet is also symbolic. We know of no particular reason why this pattern, B, was chosen to represent the sound "beeeee". Because the assignment of sign to sound is therefore arbitrary, the letter B is a symbol.