In the "Pompeiian Pizza Fresco" ®, how do we know that it's "sacrificial" and what does that mean?

Archaeologists recently discovered the Pizza Fresco in Pompeii. In an article, they wrote "From a passage of Virgil’s Aeneid, [...] it is possible to understand the position of fruits and other products of the fields, on sacrificial breads that function as 'tables'."

What does it mean that the breads are "sacrificial"? How does the position of the fruits indicate that, and what does even "table" mean in this context?