Outside faucet- can I fix it myself without calling a plumber?

if it froze over the winter, no; you'll need a plumber ... not hard to do, but you'd need some special tools/soldering iron, pipe dope, etc., and depending on what kind of pipe it goes into -- copper, PVC, lead, galvanized, etc., would all require a somewhat different remedy - and the bibs come in 4 sizes ... and you can't tell from the outside of your home. NOW -- is it the FAUCET itself, or where the hose connects to it? if it's where the hose screws onto the threads, you may only need a new hose washer ... if the threads haven't been damaged ....

We bought the end piece (it goes under the house about a foot to attach to the water pipes) at a home improvement store. It was not difficult to take off the old one and replace it with the new one. The clerk was very helpful in Menards, he said they freeze and crack in a hard winter so he recommended the kind that does not allow the water to set at the faucet end, but it leaves the end clear of water until you turn it on again. I for get how it works, but it saves having to replace them every year due to ice in the faucet or in the gaskets of the faucet.

You can repair the leak or replace the faucet.

https://www.todayshomeowner.com/video/how-to-repair-a-leaking-outdoor-faucet-hose-bib/

https://www.wikihow.com/Replace-an-Outdoor-Water-Faucet

https://www.youtube.com/watch?v=R1FFBbiJdNU