MmWave communication is one of the cornerstones of future generations of mobile networks. It is recognized by its multi-gigabit transmission capacity, high propagation loss, and sensitivity to blockage. The high rate provided by mmWave links can potentially unlock emerging applications such as online ultra-high-definition video streaming, augmented and virtual reality, and instant file sharing for 5G networks. While the performance of mmWave links has been thoroughly investigated either by simulations or testbeds, the behavior of this technology in real-world commercial setups has not yet been thoroughly documented. In this paper, we address this gap and present the results of an empirical study to determine the actual performance of a commercial 5G mmWave cell through on-field measurements. We evaluate the signal and beam coverage map of an operational network as well as the end-to-end communication performance of a 5G mmWave connection, considering various scenarios, including human body blockage effects, foliage-caused and rain-induced attenuation, and water surface effects. To the best of our knowledge, this paper is the first to report on a commercial deployment while not treating the radio as a black box. This measurement analysis provides valuable information for researchers and 5G verticals to fully understand how a 5G mmWave access network operates in real-world and operational conditions, with buildings, humans, trees, water surfaces, etc.