Wordpress expert optimising

Hi,
Hope everyone is well.
I have a question regrading the optimization of some of my word-press blogs i go into this in a second before i do that just want to say prior to a previous post regarding word-press security which i was involved in.
The plugins
Login lockdown
Wp secure

have done a great job

Now further to what i was talking about is there a word-press expert out there or some with some great knowledge on word press that can help.
Ive set 2 new websites up and when i view the websites in Google in the serps their url reads

domainname/tag/(tagname)

so instead of just the straight forward domain home page its getting the added?
In the permalink i have added a custom name so this isnt the issue

Also when one clicks on the domain through the serps it goes to the home page (where i have three posts)
and at the top of the post (very top) it says
Posts Tagged 'tag name'

Never had this on any of my other sites
im using the same theme? and same format with the setup?

PLEASE PLEASE can someone help me out and resolve whatever s causing this.

Many Thanks
Tom