Every piece of music has an overall plan or structure, the "big picture", so to speak. This is called the form of the music.
It is easy to recognize and grasp the form of some things, because they are small and simple, like a grain of salt, or repetitive, like a wall made of bricks of the same size. Other forms are easy to understand because they are so familiar; if you see dogs more often than you do sea cucumbers, it should be easier for you to recognize the form of an unfamiliar dog than of an unfamiliar sea cucumber. Other things, like a forest ecosystem, or the structure of a government, are so complex that they have to be explored or studied before their structure can be understood.
Musical forms offer a great range of complexity. Most listeners will quickly grasp the form of a short and simple piece, or of one built from many short repetitions. It is also easier to recognize familiar musical forms. The average American, for example, can distinguish easily between the verses and refrain of any pop song, but will have trouble recognizing what is going on in a piece of music for Balinese gamelan. Classical music traditions around the world tend to encourage longer, more complex forms which may be difficult to recognize without the familiarity that comes from study or repeated hearings.
You can enjoy music without recognizing its form, of course. But understanding the form of a piece helps a musician put together a more credible performance of it. Anyone interested in music theory or history, or in arranging or composing music, must have a firm understanding of form. And being able to "see the big picture" does help the listener enjoy the music even more.