No, there are many suns (or stars) in the universe. Our sun is just one star among billions or even trillions of stars in the vastness of the cosmos. In fact, the sun is a relatively ordinary star in terms of its size and properties. There are stars that are much larger, smaller, hotter, or cooler than our sun.
The universe is incredibly vast, containing billions of galaxies, and each galaxy can contain millions or billions of stars. Additionally, there are numerous star systems with multiple stars, known as binary or multiple star systems, where two or more stars orbit around a common center of mass.
So, while our sun is important for us because it is the star at the center of our solar system, there are countless other suns scattered throughout the universe.