question What types of domains earn more parking revenue?

Names are like these are not going to get any type-in. Only backlinks if they have history.
So newly-registered domain with no history will get visit from the bots only.
Qualified human traffic will not materialize out of the nil.

Examples of names that will get parking:
- the COM of a name where another extension is a popular website - ex mycoolsite.net is a popular blog - and you register mycoolsite.com
- websites that were previously developed (this traffic usually tails off after a year or two)
- short words in .COM
- medium length words with high search volume, in .COM
- typos of popular brands / websites (kind of dangerous to play here)

Also - in terms of portfolio management - review the parking revenue of every name before renewal. Any name that didn't earn back it's renewal cost, drop (unless it has other premium value). Follow this strategy, and in a few years, you'll have a money earning asset

As for your question "what does cpc mean?"
It means cost per click. It's a ppc term used in online advertising.
As for $600 click, not going to happen. You'd be lucky to get a $6 click. Maybe somebody else knows differently from their experience.

The clicks with CPC 600 USD and higher "happen" but not frequently. Usually those are keywords with a couple of tens of searches per month on Google for exact phrase. So getting those is quite comparable to winning a lottery. I estimate 99.9 percent of clicks on a parked page are below 1 USD per click.

The domain s which gets traffic

Its not traffic that gets clicks and make revenue with parked domains it's quality traffic. Someones interested in a topic there less likely for instance to click a link that's off due to keywords and such where as someone who see that exact thing there looking for as a link or came there to see the product they are more likely to click it.

Earn money for parking or earn money from parking ,this is a problem.