Each motif tells a story and represents aspects of life in the community.
The motif across the chest is called Hakaku and represents a tool they use to cut the grass to feed the animals. Because of its shape, it's also commonly known as the claws of the puma, one of the three sacred animals for the Inkas.
The motif on the shoulders that looks like an S represents the tool they use in the community to work the fields, which has the same shape. It's called cuty in Quechua, and the motif is named after it. Some women weave a line or dots in between the cutys, some don't. So even if your friend buys the same piece, the motifs may vary a bit, which makes every piece unique.