両手をより速くこすればこするほど、両手はそれだけ暖かくなってくる。

、。

The faster you rub your hands together, the warmer they get.

Literal

Both-hands [object-を] faster rub [the-more-ば] [the-more-ほど], both-hands [topic-は] that-much warmer become-come.

~ば~ほど ('the more X, the more Y') here pairs with a comparative — より速くこすればこするほど. ~なってくる uses the auxiliary ~てくる to mark a change developing over time — 'comes to be warmer' rather than a static 'is warm.' A useful pairing that captures gradual physical change.