This lecture covers the concept of bases and vector subspaces in R³, discussing how a set of vectors forms a base if it is impossible to express one vector as a combination of the others. It explains the properties of bases, such as being linearly independent and generating the entire space. The lecture also explores examples of bases in R³, including canonical bases and non-generating bases. The instructor demonstrates how to determine if a set of vectors forms a base by checking for linear independence and spanning properties.