This lecture covers the concept of pressure in technical systems, including different units of pressure measurement such as Pascals, bars, and atmospheres. It explains the relationship between pressure and force per unit area, as well as the use of pressure in hydraulic systems. The lecture also delves into the Bernoulli equation and its application in calculating pressure drops in pipes, considering factors like flow rate, pipe diameter, and roughness. Additionally, it discusses the importance of pressure conservation in maintaining a constant flow rate and the impact of pressure losses due to friction and obstacles in the system.