I understood that imperative is the tu and vous form without the pronoun. Why then is it donne moi ton argent and not donnes moi? Thanks
Relox84 gave a good answer, you should know that in France young schoolchildren (and also many adults) have trouble understanding that the "s" disappears with some verbs. Not always very logical the French conjugation. Good luck.
It's not just tu and vous, it can also be nous. Allons-y means "let's go". In the tu form, the s is always dropped.
It's actually a bit more complex than that: only verbs ending in -es in the tu-form drop it in the imperative, otherwise it's kept:
tu manges -> mange !
tu offres -> offre !
tu finis -> finis !
tu fais -> fais !
tu prends -> prends !
tu dors -> dors !
One way to think of it is that it takes the form of the je-form rather than the tu-form.
The two other forms of the imperative are exactly the same as the vous-form and the nous-form.
Four verbs have an irregular imperative based on the subjunctive stem:
savoir -> sache/sachons/sachez
vouloir -> veuille/veuillons/veuillez (but only veuillez is used in practice)
être -> sois/soyons/soyez
avoir -> aie/ayons/ayez
Also note that aller irregularly drops the s in the tu-form: tu vas -> va!
And all verbs that drop the s in the imperative regain it when the pronouns y or en come after: vas-y, manges-en.
As said, you don't have to put an "s" for the "tu" (the second singular person) just because it's a rule.. But have a look to the exceptions!! :)
An other article in english this time : https://www.thoughtco.com/introduction-french-imperative-mood-1368858