[usmhot]

The Universe is spatially finite.

Indeed, its finite and unbounded - i.e. there is no edge.

Simple explanation of something having no edge is:
imagine you are a one dimensional being living in a ring - you can only move forwards or backwards within the ring (there is no other direction as there is no other dimension). If you move forwards indefinitely you eventually get back to where you started from without ever reaching an edge or boundary.

Before Einstein the prevailing believe was in an infinite static Universe, but solutions to Einstein's General Relativity equations consist of finite unbounded Universes (causing him much consternation, cos he had grown up believing the Universe to be infinite).

At this stage the evidence for a Big Bang is pretty much unassailable. And, given that the Universe started as a singularity - i.e. spatially restricted to a single point - and a limited time has passed since then, and nothing can travel faster than the speed of light (relative to anything else) it could never have become (yet or in the future) spatially infinite.