A vector is the simplest type of data structure in R. Simply put, a vector is a sequence of data elements of the same basic type.
As in C the elementary data types are int, char, float etc. similarly there is vector in R. A vector is a constituent of an array and can be of integer type, character type, logical type and so on.
1D array of homogeneous elements is a vector.
2D array of homogeneous elements is a matrix.
Any data structure with more dimensions comes in the category of an array.