A lot of people talk about slots and I have no idea what they're saying ^^;

A "slot" is basically asking for a copy of a CW. On the previous CW system, the usernames of people who would be receiving copies had to be filled in when the item was originally submitted (or when subsequent batches were submitted), so you would ask to reserve your slot in that list. Nowadays, it's basically just an old habit of the collective userbase since that system no longer exists and if an item isn't just outright buyable in someone's CW shop, you're technically asking for an invite to buy a copy instead c:

Thank you!!

What do people mean when they talk about two slot or three slot items in a trade?

Without an example or context, I'm not sure, sorry! "Slot price" is whatever price the item sold for when it was slotted or put into a CW shop but I haven't seen two slot or three slot items referenced before. My guess would be they're asking for two or three slot-priced items in exchange for the item(s) in the trade, but since slot price varies, I'm not sure what they mean.

If the description just says "Slot" though then that means they're asking for slot price for each item in the trade

Ahhh I see. Thank you so much!