In section 617 of The Will to Power, Nietzsche says:
“To stamp the character of Being on Becoming - that is the highest will to power.”
If this is the highest will to power, what is the will to power as such? Two sentences onward in the same passage, Nietzsche gives a clue as to the answer of this question:
“That everything returns [wiederkehrt] is the closest approximation of a world of Becoming to a world of Being: - summit of the meditation.”
The word here translated as “meditation” is Betrachtung. This word contains the verb trachten, cognate with “try”. So the summit of the attempt to think through a stamping of Becoming with the character of Being is not such an actual stamping, not a reconciliation of both said worlds, but only an approximation of the two. The summit is the closest approximation, which follows from the highest will to power - the will to actually reconcile the two. Nietzsche, the philosopher of will to power, embodied this highest will to power and expressed it in the doctrine of the eternal return of the same (which is really the same return of eternal Becoming, but nevermind that now).
If the highest will to power expresses itself as the closest possible approximation of a world of Becoming to a world of Being, then the will to power as such is the will to approximate Becoming to Being.
Thus the will to power is the will to affirm (make firm) Becoming. The Nietzschean verb usually translated as “to affirm” is bejahen, “to say Yes to”. And “yes” literally means “so be it”, using a form of the s-root of “to be”- which root was originally a different verb, which meant “being” in the Parmenidean sense, whereas the b-root rather meant “being” in the Heraclitean sense (Becoming/phusis). So saying Yes to something is to express the wish that that - Becoming - may be (endure, remain firm). But the German ja, as the English “yea”, does not contain this s-root of “to be”. It just means “so, thus”. It implies the wish that “so shall it be” - “thus!” (as it is now).
I propose to translate Wille zur Macht (“will to power”) as “will to might”. For “might” (which is cognate with Macht) is related to “make”, which etymologically signifies a “kneading”. Thus the formless and only relatively solid material of Becoming is “kneaded” into forms, “made firm”, by the will to might. This always seeks to approximate Becoming to Being, to create “something” (a “thing”, a “being”).