The noun לחם (bread) does not come in plural, but its adjectives come in plural.

And the noun לחם sometimes comes in masculine and sometimes comes in feminine. And when it is written והיתה ללחם לאזכרה ואכלוהו (that it may be to the bread for a memorial-part …. and they shall eat it)⁶⁷⁰, the pronoun והיתה refers to the gift-offering, since the noun לחם comes in masculine.

Leviticus 24:7-9 says,ונתת על המערכת לבנה זכה והיתה ללחם לאזכרה אשה ליהוה. ביום השבת ביום השבת יערכנו לפני יהוה תמיד מאת בני ישראל ברית עולם. והיתה לאהרן ולבניו ואכלהו במקום קדש כי קדש קדשים הוא לו מאשי יהוה חק עולם (And you shall put pure frankincense with each row, that it may be to the bread for a memorial-part, even an offering made by fire to the LORD. Every sabbath day he shall set it in order before the LORD continually; it is from the children of Israel, an everlasting covenant. And it shall be for Aaron and his sons; and they shall eat it in a holy place; for it is most holy to him of the offerings of the LORD made by fire, a perpetual due).

The verb ואכלוהו in the last verse means “and they shall eat it”, where “it” comes in masculine; thus, “it” must refer toלחם*. And the pronoun והיתה in the first verse, which means “that it may be”, comes in feminine; thus, “it”must refer to the gift-offering⁶⁷¹.*

footnotes: ⁶⁷⁰ Leviticus 24:7-9. ⁶⁷¹ Malbim, HaTorah v’HaMitzvah Emor 232.