Learn French: Le client veut fumer, mais c'est interdit. - The client wants to smoke, but it is forbidden.

Yes! Veut comes from the verb vouloir (to want). It behaves exactly like the verb pouvoir (to be able to). For 'he', you say il peut (he can) and il veut (he wants). Both are irregular verbs but follow the exact same spelling patterns, which is why they are often learned together.

Why is fumer in its dictionary form (infinitive) instead of being conjugated?

In French, when you have two verbs right next to each other, only the first one gets conjugated. Since veut is already conjugated to match le client, the second verb fumer (to smoke) stays in its infinitive form. This is just like saying 'wants to smoke' in English.

Why is it c'est instead of ce est?

In French, when a short word like ce (meaning 'it' or 'this') is followed by a word starting with a vowel, like est (is), the first vowel is dropped and replaced with an apostrophe. This makes the phrase flow better when spoken and is a required rule, not just a casual shortcut.

Would interdit (forbidden) change spelling if the forbidden thing was feminine?