According to Law 3 - The Players - 1. Number of players:
A match is played by two teams, each with a maximum of eleven players;
one must be the goalkeeper. A match may not start or continue if
either team has fewer than seven players.
So, usually we have 11 x 2 = 22 players on the field.
According to Law 3 - The Players - 2. Number of substitutions:
The competition rules must state how many substitutes may be named,
from three to a maximum of twelve.
So, there can be maximum of 12 x 2 = 24 players on the bench, resulting in total of 24 + 22 = 46 players.
But as you can see, the exact number of players sitting on the bench is determined by the competition rules. In Premier League, La Liga and most other leagues playing under federations associated with UEFA, and also in UEFA Champions League, the number of players sitting on the bench is 7, resulting in a total of 11 x 2 + 7 x 2 = 36 players. However, on the international level, the number of players sitting on the bench is usually maximal, i.e 12, again resulting in total of 46 players.