There are two possible answers to this. If the H is listed next to the ER (earned runs), SO (strike outs) and BB (base on balls), it is a number of hits that the pitcher gave up. However, if you see it right after the pitcher's name: Joe Bozo (H, 1), then it stands for a "Hold" and the number right after that is the number of Holds he has been credited:
Hold
A Hold is credited any time a relief pitcher enters a game in a Save Situation, records at least one out, and leaves the game never having relinquished the lead. Note: a pitcher cannot finish the game and receive credit for a Hold, nor can he earn a hold and a save.
Reference:
http://baseballtips.com/glossary.html
sacrifice
On Base Percentage
Win
catcher interference
Wild Pitch
Caught Stealing
Bi Sexual
It stands for a "blown save"
Walks plus hits per innings pitched.
turnovers
Difference
k stands for strikeout looking K stands for strikeout swinging