It depends on what's leaking.
If it's just the hose then it's pretty straight forward, turn off water, remove hose replace with new one.
If it's leaking from the pipe that's protruding from the wall then it gets a bit harder but it should fix the problem for a good while.
Your gonna need a new shut-off valve and a blowtorch. You don't really need a fire protecting cloth, just don't burn your house down.
1.
Unscrew the faucet supply line from the shutoff valve with a small adjustable wrench. ( Make sure you turned off all the water going to the pipe. )
2.
Clamp a pair of locking pliers to the old soldered valve and heat the valve with a propane torch. When the solder melts, twist the valve back and forth while pulling it off. Wipe the end of the pipe with a cloth immediately after removing the valve to get rid of old solder. (Wear a glove so you don’t burn your hand.)
3.
Slide the compression nut, then the ferrule, onto the copper water pipe. Lubricate the compression threads with a small amount of pipe dope. Tighten until firm with a pair of adjustable wrenches and then turn the wrench an additional 180 degrees. Reconnect the faucet supply line after the shutoff valve is in place.