This file defines strength influence on characters abilities like allowable weight that could be taken by character or to hit bonus.
The first row (titles of columns ) is filled by the names of features affecting of PC (like TO_HIT = to hit bonus ).
The first column is filled by value of strength of character.
The rest columns are filled by values for given strength - pretty obvious from names I suppose.
In BG2 ToB we have:

2DA V1.0
 0
   TO_HIT   DAMAGE   BEND_BARS_LIFT_GATES      WEIGHT_ALLOWANCE
0    -20      -20             0                       0
1    -5       -4              1                       1
2    -3       -2              2                       3
3    -3       -1              3                       5
4    -2       -1              4                       15
5    -2       -1              5                       15
6    -1       0               6                       30
7    -1       0               7                       30
8    0        0               8                       50
9    0        0               9                       50
10   0        0               10                       70
11   0        0               11                       70
12   0        0               12                      90
13   0        0               13                       90
14   0        0               14                       120
15   0        0               15                       120
16   0        1               16                      150
17   1        1               18                      170
18   1        2               20                      200
19   3        7               50                      500
20   3        8               55                      600
21   4        9               60                      700
22   4        10              65                      800
23   5        11              70                      1000
24   6        12              75                      1200
25   7        14              80                      1600