Essentially @MaximilianPress hit the nail on the head. sgRNA is a major feature of SARS-CoV-2.
This is where the 5' UTR is spliced at numerous locations in the genome, such that although it is a single stranded positive sense RNA genome it behaves like a segmented viral genome because it is translated as a series of sub-genomic RNA molecules. So influenza is a classic example of a segmented genome. SARS-CoV-2 is more slightly complicated because it is using frameshifts to achieve to achieve the different sgRNAs.
However it isn't a particularly strong example of frameshifts because virus such as HBV (hep B) are pass masters, where two different proteins are encoded within a single locus.
My personal view is that slippage isn't operating here, unlike say HIV, but that it is a function of the sgRNA construction, thus N protein occurs on one sgeRNA and ORF8b occurs on a second sgRNA and sg signal is within the N protein.
If SARS-CoV-2 is your thing then stuff like this is a big player in interpreting bioinformatic output.