It’s just that where English (“mean”) or German (“bedeuten”) have one word to express “to intend” / “to signify”, French does not have one single word and uses a periphrasis.
Here are two different uses of vouloir dire:
Ça ne veut rien dire.
(It doesn’t mean / signify anything. / Das bedeutet gar nichts.)
Qu’est-ce-que tu veux dire ?
(What do you mean? Note that German in that case also uses the periphrastic: “Was willst du damit sagen?”).
The verb is actually vouloir dire together, which means to mean, to signify. In other words, literally “That’s meaningless”, “That means nothing”, or more idiomatically, “That makes no sense”.