II. What is it For?
A. In general, the Conditional is for the hypothetical--what might or could happen, what may be possible, but may depend on conditions (if). It can also be for a polite request (see vouloir, for example). In many cases, it will be the equivalent of "would" in English. Note: Remember, the use of "would always" or "used to" for a regular occurring event in the past would be in the Imperfect, not the Conditional.
B. Here are three very, important and useful verbs for beginners in the Conditional.
1. vouloir: to want / COND: would like -- Je voudrais
(a) The Conditional softens the "I want" of the present tense of the verb, making it sound more polite.
(b) Asking, "Voudriez-vous...?" can be used for "Would you like...?"
2. devoir: must, have to / COND: should -- Je devrais
3. pouvoir: to be able, can / COND: could -- Je pourrais
(a) The Conditional changes "can" to a possibility (could).
(b) Asking, "Pourriez-vous...?" can be used for "Could you...?"