English: “If he offers” — I might think it is obligatory; therefore the Torah says “if he offers,” teaching that it is only optional (voluntary).
In Sifra: Conditional ki blocks a reading of this section as chovah. Without that hinge, “he shall offer” language might have been taken as imposing a duty. Sifra settles the unit as nedavah: when a person chooses to draw near with a gift, these are the rules.
Type of Learning
Force of conditional language — ki yakriv marks reshut, not gezeirah (obligation).
What Is Learned
This opening of Vayikra governs voluntary offerings (nedavah), not fixed-obligation offerings such as chatas and asham. The word ki (“if / when”) is what keeps the section in the domain of free-will gifts. The rest of the chapter’s details ride on that classification.