I'm a bit confused on bike shoe terminology. Particularly regarding Look KEO Plus Pedals - what is required to use them? I'm a bit confused on terminology.

Clipless pedals are the clip-in style pedals. Correct?
Then the cleat are the shoes you wear? Or are cleats just bottom attachments for any cycling shoe?

A used cycle I'm looking at getting has Look KEO Plus Pedals on it which says it comes with Cleats. The shoes the guy had didn't fit though. I'm not fully understanding if any bicycle shoe will fit the Look KEO Plus Pedal or if I need a particular cleat and/or shoe for it?

Terminology index - a list of bike part names and cycling concepts has a mention of Look Pedals but doesn't really go into any detail that would answer my question.
Cleats are the bottom attachment to shoes. Most road shoes use a 3 hole attachment, which is a standard size. Most pedal manufacturers have their own cleat style, but all 3-hole cleats use the same spacing as far as I know.

Your pedals may come with suitable cleats if you're buying them new, if not make sure you buy 'look keo' compatible cleats. There is another (old) style of look cleat that is incompatible. So long as it says keo you will be fine though.