What It Scores
JO is a valid word in the tournament list this site uses. Tile values only, before any premium square: 9 in Scrabble, 11 in Words With Friends, 11 in Wordfeud. The letters break down as J8 O1.
Longer Words Containing JO
JO appears inside each of these, which is what makes it worth knowing as a hook.
Next: the Word Unscrambler for any letters at all, and the two and three letter lists. Full entry and definition at Merriam-Webster.