The domain I just registered the last week shows CPC of $5.34.
Websites and domain software that sell domains, in particular expired domains, will often list a "CPC" (Cost Per Click) along side of them. The domain itself does not have any CPC value however, it's the keyword contained within the domain name, such as
example being the keyword in
example.com, that determines the CPC value, not the domain itself.
These sites derive this value by programatically looking for keywords in the domain name and plugging that into Google AdWords, which will return a (fluctuating) CPC value for the keywords themselves.
Search engines like Google however no longer factor in exact match domains (EMD) into searches, so consequently there is very little value in them directly, unless they are very common keywords that might be considered type-ins (i.e., keywords that people might type directly into the address bar of a browser, followed by
.com), which can amount to some traffic.
So although the domain might contain keywords that have a CPC value, the domain itself doesn't have any CPC value. It's just a marketing ploy used to sell domain names based on the antiquated notion that search engines give EMDs more weight (which is no longer true).
If the domain is related to business and the content I created is
related to some dating tips, ie, irrelevant content on the domain,
does this decrease the CPC of the domain?
If you display content that is not relevant to the keywords users are searching for, the CPC for the keywords in the domain name will not change, but ads targeting the keywords will likely not be displayed on your site, and you may even get banned from AdSense (or whatever ad platform you're intending on using) for displaying content unrelated to the keywords you applied for.
In order to reap any benefit from the keywords in the domain name, you'd need to target the content of your site to match those keywords, and use those keywords (not domain) within that content. So if your domain had keywords related to "business", then you'd need to have content related to business, not "dating tips". However, this is really no different than using a domain without any keywords at all.
In short, unless the domain name can help build brand-name recognition and traffic for your site (e.g., because it's easy to remember), you're free to use your domain for any other keywords and content related to them, since it really won't matter in the eyes of search engines and ad platforms.
For more information on what keywords are, how the CPC is determined for them, and how to target content for keywords, see: Google AdWords - Keywords