Battery terminal on my car is loose and can't be tightened any more. How do I fix it?

2002 Ford Focus ZTS 150k miles

I assume you mean the cable can't be tightened. Should be easy to replace it.

Otherwise, if it is actually a battery terminal, you replace the battery.

Replacement cable ends are available at the auto parts store or replace the cable.

Put some vice grips on it and squeeze…

Tape

Is it a top post battery or a side post battery?