A uniform numeric vector is a vector whose elements are all of a single numeric type. Guile offers uniform numeric vectors for signed and unsigned 8-bit, 16-bit, 32-bit, and 64-bit integers, two sizes of floating point values, and complex floating-point numbers of these two sizes. See SRFI-4 - Homogeneous numeric vector datatypes, for more information.
For many purposes, bytevectors work just as well as uniform vectors, and have the advantage that they integrate well with binary input and output. See Bytevectors, for more information on bytevectors.