Labor productivity, as measured by output per worker or output per worker hour, is a function of many factors. Let me mention a few in the framework of growth theory. Many economists consider at least three factors that determine economic growth: human capital, physical capital, and the “efficiency” with which human capital and physical capital are used to produce output (the jargon is “Total Factor Productivity”, or TFP). “Labor productivity” in the question is affected by all these three factors.
First, labor productivity is clearly affected by human capital, the skills and capabilities of workers, which in turn is determined by many factors, including education, training, and health. So anything that improves education, training, and health is likely to increase labor productivity.
Second, labor productivity also depends on stock and quality of physical capital. Physical capital includes durable production inputs such as infrastructure, factory buildings, machines, and computers. Tractors and airplanes have vastly improved the labor productivity of U.S. farmers. But not only new generations of physical capital improves labor productivity, the quantity of physical capital also matters for productivity, at least before saturation. More assembly lines in a factory usually means less downtime of production. More computers in the firm means fewer workers have to share computers with others.
Third, more efficient ways to combine human capital and physical capital also contribute to increasing labor productivity. Technology and organizational advances play important roles in this regard. Assembly lines, telecommunications, and the invention of modern firms fall into this category. Note that some technological progress is embodied in the physical capital, e.g. cellphones and computers make workers more efficient in coordinating production.