When scott says, "human resources is one of the most important things we do in our business," what is he referring to?

He is referring to the situation against other competitors.
In business environment, people are constantly moving(either to pursue another career opportunities or stolen by competitors)
To handle this, companies will always have to train ther employees with new skills and find new talents to fill them in and expand their production capabilities.

The business cycle is the periodic but irregular up-and-down movement in economic activity, measured by fluctuations in real gross domestic product (gdp) and other macroeconomic variables. a business cycle is typically characterized by four phases—recession, recovery, growth, and decline—that repeat themselves over time. economists note, however, that complete business cycles vary in length. the duration of business cycles can be anywhere from about two to twelve years, with most cycles averaging six years in length. some business analysts use the business cycle model and terminology to study and explain fluctuations in business inventory and other individual elements of corporate operations. but the term "business cycle" is still primarily associated with larger (industry-wide, regional, national, or even international) business trends.