Basic stats:
G: Games played.
W: Number of games won.
L: Number of games lost.
%W: % of games won over total games played.
MIN: Minutes played.
POS: Possessions spent.
PTS: Points scored.
PIR: Performance index rate.
SCO +|- : Plus / Minus stat reflects the score while a player is on the floor.
TSR: True Shooting Ratio (%). Points scored over points tried.
TS%: True Shooting (%). Points scored over adjusted points tried. Formula is PTS / 2*(FGA+.44*FTA).
eFG%: Effective field goals (%). Formula is (FGM + .5*3PM) / FGA.
TRR: True Rebounding Ratio (%). Rebounds grabbed while on the floor over rebounding options.
AST: Assists.
ST|TO: Difference between number of steals and number of turnovers made.
BLCK: Difference between number of blocks and number of rejected shots.
FOUL: Difference between number of fouls committed and number of fouls drawn.
SHARES: In game boxscores, is the importance of a player on a game. Formula is (PTS + FGM + FTM - FGA - FTA + DREB + (.5 * OREB) + AST + STL + (.5 * BLK) - PF - TO) / (GmPTS + GmFGM + GmFTM - GmFGA - GmFTA + GmDREB + (.5 * GmOREB) + GmAST + GmSTL + (.5 * GmBLK) - GmPF - GmTO), where Gm figures correspond to total Game (sum of both teams) figures.

Performance stats:
Positive:
1P: PIR points due to 1p shots made.
2P: PIR points due to 2p shots made.
3P: PIR points due to 3p shots made.
REB: PIR points due to rebounds grabbed.
DREB: PIR points due to defensive rebounds grabbed.
OREB: PIR points due to offensive rebounds grabbed.
AST: PIR points due to assists.
STL: PIR points due to steals.
BLCK: PIR points due to blocks made.
DRW: PIR points due to fouls drawn.
TOT+: Total positive PIR points.
Negative:
1P: Negative PIR points due to 1p shots missed.
2P: Negative PIR points due to 2p shots missed.
3P: Negative PIR points due to 3p shots missed.
TO: Negative PIR points due to turnovers.
REJ: Negative PIR points due to shots rejected.
FOUL: Negative PIR points due to fouls committed.
TOT-: Total negative PIR points.


Shooting stats:
PFG: Points per field goal tried.
2|3 EQ: Equilibrium at shooting. The more close to 0, the more balanced shooting between 2p and 3p shots. Positive (negative) value: they should try more 2p (3p) shots and less 3p (2p) shots.


Rebounding stats:
1P: Rebs from 1p shots grabbed.
1P%: Rebs from 1p shots grabbed over total rebounding options while on the floor.
2P: Rebs from 2p shots grabbed.
2P%: Rebs from 2p shots grabbed over total rebounding options while on the floor.
3P: Rebs from 3p shots grabbed.
3P%: Rebs from 3p shots grabbed over total rebounding options while on the floor.
TRR: True Rebounding Ratio (%). Rebounds grabbed while on the floor over rebounding options.


Refereeing stats:
FT|TT%: Free throws tried over total throws tried.
OF|TO%: Percentage of turnovers that are due to offensive fouls.


Advanced stats:
ORAT: Offensive rating. Points scored every 100 possessions spent.
DRAT: Defensive rating. Points scored every 100 possessions spent by the opponent while on the floor.
DIFF: ORAT-DRAT.
TO|POS: Percentage of possessions finished with a turnover.
ASS|TO: Ratio between assists and turnovers.
DEF: Defensive plays. Blocks + Offensive fouls drawn + Steals.
OPP3P: 3p% (made over tried) of opponents while on the floor.
OPP2P: 2p% (made over tried) of opponents while on the floor.
USG%: Usage percentage is the percentage of team plays used by a player while he was on the floor. This is NOT an estimation, it's the real thing.
ASS%: Assistance percentage is an estimation of the share of team mates points that are due to the assists granted by a given player.