Yes, it's the pulley on the crankshaft.
You need to find a way to keep the pulley from turning while you try to wrestle the bolt loose. On slotted pulleys I have braced metal bars (screwdriver shafts) through the pulley and caught them on something solid on the backside. A good strap/chain wrench may grab with enough grip to do it, I used a strap wrench when I put the pulley back on (100k miles ago so it's held) but haven't tried it for removal.
On the Focus, I used the starter to turn the motor with a breaker bar/socket on the pulley and braced on the garage floor.....this is the not-so-safe-way I think he is mentioning. VERY IMPORTANT, you must have the plug wires or coil unplugged or the motor will fire.....this is bad with a loose pulley bolt ! Also the breaker bar will probably go flying across the garage (mine did) so it's important not to have any body standing around or anything breakable nearby. If I would have thought about it more, I would have draped a towel over the breaker bar handle or something.
Panties aren't the best thing in the world but they are next to it.
I would rather drive the slow car Rusty built than the slow car I built.
Do your own repairs, it's not rocket surgery !!