Defining what Preparing Spells mean

[danii956]

In the book, it says,

Each day, usually in the morning, spellcasters prepare spells to replace those they have used.

and

Spells prepared but not used persist from day to day; only those actually cast must be replaced.

My question is does this mean that magic users must prepare a specific spell and once that spell is used, it cannot be used again until prepared the next day? So for example, I prepare Light and Detect Magic as my 1st level Cleric spell. If I use Light, then I can no longer use Light again for the rest of the day? If so, does that mean that magic users in this game don't have spell "slots" but spells prepared to be casted?

[chiisu81]

My question is does this mean that magic users must prepare a specific spell and once that spell is used, it cannot be used again until prepared the next day?

That is correct.

So for example, I prepare Light and Detect Magic as my 1st level Cleric spell. If I use Light, then I can no longer use Light again for the rest of the day?

Also correct. A Cleric would need rest like a Magic-User, and then pray to his or her deity for spell preparation.

If so, does that mean that magic users in this game don't have spell "slots" but spells prepared to be casted?

Yes, prepared is how it's worded in the Core Rules. You can still think of it as available "slots", different numbers of slots of different spell levels. Resting/sleeping and then preparing refills those slots, and they're used/emptied whenever the spells are cast.

[Dimirag]

The game uses spell slots that are filled with specific spells. Once the spell is used is no longer available (along with the corresponding slot).

Each new day every slot not containing a spell is recovered, and can thus be filled again with specific spells.