As others have noted, those are some seriously big lights.
The lights are designed for 12 volts. If you want to put four of them in series, you need 48 volts. Finding a portable 48 volt battery isn’t going to be easy, so you’ll probably be best with four 12 volt batteries also in series. As was previously mentioned, this is probably easier to wire them in parallel. Then all you need is one 12 volt battery.
These are 20 watt bulbs, which means they draw 20/12 = 1.67 amps. That’s a lot of current. Your wire will need to handle that much current, so you’d be best using something no thinner than about a #18 wire. You’ll also need a battery that can supply that much current. Your basic Joe Average flashlight cell won’t work. They aren’t designed to crank out that many amps.
If you parallel the lights, you’ll need 4x1.67 or 6.67 amps. Lesser voltage, more amps, same amount of total power.
The proper way to figure out how long the battery will last is to use the discharge curves from the battery manufacturer. The “close enough” quick and dirty way is to just take the amp-hour rating and divide it by 2. If you powered these from a 12 volt motorcycle battery rated at 12 amp-hours, you could therefore expect your lights to last about an hour before the battery runs out (12 amp-hours divided by roughly 6 amps = 2 hours, divide by 2 and you get 1 hour).
As others have noted, you can get the same amount of light for significantly less current (and therefore a significantly smaller battery) by switching to LEDs.
12 volts also isn’t high enough in voltage that you really need to worry about electrocution. 48 volts though is getting up into the range where that amount of voltage can be dangerous if you touch it. No matter what you use, you are dealing with enough current to potentially melt and/or catch things on fire if you have a short or a bad connection. Be careful. Heat from the bulbs may also be an issue if this is something to be worn.