Array is a collection of the same type (as I commented below, this rule can be bent though). With the use of array, you can place similar elements next to each other in the memory, handle them together, iterate through the elements in the array. It makes handling them easier and also can consume less memory than simply just declaring them one by one. (This is due to memory alignment and padding.)
Please note C and C++ are not exactly the same.
For arrays in C you would typically do
oo create an array of 10 integral numbers. This works just as fine in C++, but C++ has various collections available that makes life easier. For instance the vector:
And here is a tutorial on C arrays: https://www.programiz.com/c-programming/c-arrays