Maxime arrose-les fleurs de son jardin. Maxime waters the flowers of his garden. Maxime les arrose. Maxime waters them.
“Maxime” is the subject “arrose” is the verb “les fleurs de son jardin” is the direct object and it answers the question: “Il arrose quoi?”
“les” replaces “les fleurs de son jardin”. As you can see, the personal pronoun direct object “les” comes before the verb. The personal pronoun direct object always comes before the verb except when the verb is in the imperative. In this case, the personal pronoun direct object comes after the verb.