TCP = Transmission Control Protocol, just a set of rules computers use to communicate over the Internet.
TCP defines 'ports' on the computer. That's kind of an entry point. Browsing uses another port than mailing. They are numbered from 1 to 65535. Just part of the rules. The more ports you have open, the more ways somebody can enter in your computer.
A 'packet' is just a short part of a message. In TCP all messages are divided in short (up to 1500 bytes, I think) pieces, which find their own way across the Internet and are combined again at your computer.
The firewall warns you that somebody from the outside tried to find open ports at your computer, but the firewall didn't respond to that somebody. So for all purposes, he thinks there's no open port. Had it be found, the next step would have been to try to exploit it. That's exactly why you have a firewall.
See if you can set the firewall to NOT report port scans like this.
What exactly does it mean when my firewall says:
"TCP Port scan detected, packet droppped".
What does "TCP" stand for? What is a "port"? And what is a "packet"?