Does that mean it can be played without an amp and it will sound like a acoustic guitar and then you can switch it to an elctric by plugging it in?
Kinda. It's basically an acoustic with pickups installed, so you can play it unplugged or through an amp. It's not gonna sound like an electric guitar, though. Just an...amplified acoustic.
An Electro-Acoustic is an acoustic with a mic inside it.

Ibanez SR506BM
Ashdown Little Giant 1000w
Peavey TVX 115+410
A big ass upright

It's an acoustic guitar with a pickup and a jack that allows you to connect to an amp and amplify the sound it usually makes.
Basically it would be about the same thing as putting a mic ,connected to an amp, near your guitar.