If the car battery is completely dead as in dead battery cells then jumping the cars battery with another car or jump starter may not work.
However sometimes you might be able to get the vehicle started when jump starting with another vehicle especially if you rev the other engine up after idling it for awhile.
Then try to start the vehicle with the dead battery while the other car is idling.
However sometimes the battery may be too dead to take even a little charge to get the car started from the other battery.
If that is the case then you'll have to buy a new battery before you can start you vehicle.
If the battery in the car or vehicle has just gone dead and it still has good cells in the battery then charging the battery up with the other car or vehicle through jump starting it should almost always work.
You might need to let the car or vehicle that is jump starting you idle for 5 or 10 minutes and then rev it up to get the battery charged up enough to get it started.