Revenue per employee is a measure of how efficiently a particular company is utilizing its employees. In general, relatively high revenue per employee is a positive sign that suggests the company is finding ways to squeeze more sales (revenue) out of each of its workers.
Labor needs vary from industry to industry, and labor-intensive companies will typically have lower revenue per employee ratios than companies that require less labor. Hence, a comparison of revenue per employee is generally most meaningful among companies within the same industry, and the definition of a "high" or "low" ratio should be made with this in mind.