Google tags and SEO

This might be a stupid question but it’s a question.
I’m a little confused here, I know Ghost is SEO friendly but

1- how do I tell google what tags I’m targeting in my posts?
Is it in the normal section of the posts where it says tags?
2- Are those same tags the one used for CPC?
3- I use my tags to be organized, but if they are used like youtube for example, so google has a better idea of what the post is about, then including a lot of tags in a post might be beneficial? Then wouldn’t my tag count get out of control? Is this the normal way of doing things?