What Smartmom is actually showing in her screenshot is how many bytes have been transfered, rather than packets transferred. A byte is a unit of measurement while a packet is how data is actually transferred, and packet sizes can be different.

To describe it at it's most basic, you can kind of think of a packet and a paper envelope. If I wanted to "send you this sentence", I would chop each word up and pack it into it's own envelope, and mail you 4 different envelopes, each with one word in it, and instructions also at the top of each one, on how to re-assemble the words in each envelope, so you can read the sentence as it's supposed to be read.

Packets are how all computers talk to each other, it goes from one computer, across the net into your computer. In the case of packet injection attacks, to someone with the skill and know-how, they can insert their own packets into the "stream" of packets being sent to your computer, with malicious intent. To show you what packets really look like, there are "Packet Sniffers" available so you can peer into each individual packet that goes through your network adapter. Here's a screenshot I just took of WireShark running on my computer:

Each individual colored line near the top is an individual packet, and the data in the highlighted packet is shown in the 2 panes below it.

To get back to securing your internet connection, hiding your SSID does help a bit, it makes it so that people just looking for open connections won't see yours pop right up in the list of available wireless connections. The downside of that is you also won't see it easily whenever you might want to try connecting with a new wireless device.

Another thing to do is to enable WPA encryption on your router, or at bare minimum, WEP (easily cracked though). As long as you know your WPA key and password, you won't really need to worry about seeing your SSID because entering your WPA Key/Password will find your router for you.

Hope that wasn't too confusing.

Google GeekDrop is your friend.