Chinese verbs can occur with words or phrases that modify the meaning of the verb, such elements are usually called complements and immediately follow the verb. One type of complement indicates the result of the verb's action or its completion. It is called the resultative complement.
In 桌子预定好了。 (Zhuōzi yùdìng hǎo le.) 好 indicates that the activity expressed by the verb has been completed: The table is booked, implying the booking is done, the procedure is finished.
Simliarly, 我的作业做好了。 (Wǒ de zuòyè zuò hǎo le.) I have finished my homework. Note that the resultative complement often appears with the aspect marker 了. The resultative complement naturally suggests that the action is conceived as a completed whole, that is, it has a perfective aspect.