With this phrase, Picasso wants to demonstrate that he thinks in a way that is uncommon and original. He tells us that most people want to know how to understand, and perhaps replicate what already exists. Their focus is on comprehension, not on creation. On the other hand, Picasso focuses on things that do not exist and wonders whether they could. This is creation.
An example of this would be Picasso's own paintings. Most painters want to represent the human form and the natural world in a way that remains close to reality. They use organic lines and realistic depictions. Picasso, on the other hand, wondered if these figures could be created with geometrical shapes, which gave him his unique, cubist style.
Another example would be Leon Theremin, who invented the theremin. This was one of the first electronic musical instruments and it does not need to be touched in order to be played. While most people ask how to play an instrument, Theremin most likely asked why an instrument could not be played without being touched. This led to his most important creation.
