UnitsPerSecond /Time

float UnitsPerSecond(float speed)

Returns the approximate distance that an object should move during the current frame to keep a constant speed in units per second.

vector2 directionLeft(-1, 0);
float speed = UnitsPerSecond(10.0f);

// move entity leftwards at 10 pixels per second
entity.AddToPositionXY(directionLeft * speed);