This is the 11601st most frequent Spanish word.
firmeza
Firmness; strength or stability in character, decision, or structure.
Here, "firmeza" refers to the strength and determination someone shows in their character or decisions.
La firmeza de su carácter es admirable.
His steadfastness of character is admirable.
In this context, "firmeza" describes the solidity and stability with which an action, specifically laying foundations, is performed.
Colocaron los cimientos con gran firmeza para que soporten el peso del edificio.
They placed the foundations with great firmness to withstand the building's weight.
Here, "firmeza" refers to speaking in a determined and confident manner during discussion.