A standard Dota 2 team has 5 players.
Dota 2 is built around two opposing teams, traditionally called Radiant and Dire. Each team fields five players, so a normal match has ten human-controlled heroes on the map. Every player controls one hero, and the team coordinates movement, combat, objectives, and resource collection.
The five-player structure supports distinct responsibilities rather than five identical roles. Teams commonly organize around core positions that need farm and support positions that provide vision, protection, initiation, or utility. The exact strategic labels and lane assignments can change, but the usual team size remains five.
A common mix-up is counting the computer-controlled units that appear during a match. Creeps, towers, neutral monsters, and other map units are not players. Dota 2 also has special or custom modes with different team sizes, but those do not change the standard answer. The five-player format comes from Defense of the Ancients, the Warcraft III mod on which Dota 2 is based.