Hi @Urzula_Franco
Canonical version of the hg38 assembly contains only main chromosomes (autosomes, X, Y) and mitochondrial sequence. The whole assembly also contains unplaced and unlocalised contigs. .p14 refers to a patch. Patches do not disturb chromosome coordinates.
Info for patches (see text below the table) Genome Browser FAQ
Also check
https://gatk.broadinstitute.org/hc/en-us/articles/360035890951-Human-genome-reference-builds-GRCh38-or-hg38-b37-hg19
Hope that helps
Kind regards,
Igor