Types and stats
AP or Attack Power - This is how high your damage is when you melee attack
AC or Accuracy - This is your chance of successful melee attacks and your chance of melee criticals. It also determines how much gun damage is done. This does not affect spell or skill accuracy.
DX or Dexterity - This is the delay between melee attacks (the lower the better). This does not affect spells or skills.
Every time you level up you will receive an increase in your stats. Depending on the build you have chosen is where you receive more stats. E.g. those in 4 stat will increase at a much higher rate than those in the 3,2 or 1 stat. You will still gain points for these stats but not as much.
You will also receive four bonus points for each level you gain. You can put these bonus points into whatever you choose but two popular choices for a sheep is magic attack and luck.
MA is how much damage you do so the higher the MA the better. Putting all of your bonus points into MA is what I highly recommend.
LK is how accurate your spells are and how likely you are to dodge a critical hit. This is ideal for PvP characters. For a PvE character isn't not really needed unless you have a 1414 build, but even then you can compound lk instead. Recommended for PvP characters but not for PvE.
Magic attack and luck
You see the advantages to putting your bonus points into both MA and LK and are thinking of adding points in both? This choice should mean you still have good MA but also good LK as well. However, it will ultimately mean you do average damage and you are average at dodging and critical hits. The best thing to do is to choose either luck or magic attack and compound the other.
HP is how many health points you have, the higher the amount the more damage you can take without dying. Some 1441 sheep put their bonus points into HP to balance it out. This is helpful for not dying but you won't hit as hard. You will also need a lot of high MA and LK equips. HP is easy enough to comp anyway.
Images used from http://wiki.ggftw.com/trickster/