We're introduced to a speaker who we know—thanks to a clue from the title—is describing a Latin deli. We're told about the cash register, the kinds of food for sale, and finally the lady behind the counter. She's not pretty, nor does she seem to be of any particular age. She's selling "canned memories," though, so we guess that her store is pretty special.
In fact, she attracts a host of customers—Puerto Ricans, Cubans, Mexicans—each talking to her about one topic or another. It turns out that they enjoy speaking to her in Spanish. She's a friendly and familiar face. Her store is also stocked with items that remind these folks of home, which is why they're willing to pay more for them at her store. As the poem ends, we realize that this is more than a shopping trip for these people. It's a way for them to connect to a lost homeland.
Clearly, those pricey plantains are worth it.