Integration is mainly about a few things. (Note: These are all mathematically synonymous!)
It can be about being the “AntiDerivative” of a Derivative (Thanks to the Fundamental Theorem of Calculus).
Thanks to some really cool Math, it can be about calculating the area under the function . Or really, any volume as well (Volume by Slicing). This also comes with the idea of calculating the volume of a solid that was created when rotating a function (or pair of them) around the x-axis (Solids of Revolution)
You can also do Integration by Parts