"Dych chi'n nabod Dewi Lingo?"
Translation:Do you know Dewi Lingo?
Both nabod and gwybod are compounded forms of bod ("to be").
Nabod is a short form of adnabod, and its first element descends ultimately from Proto-Indo-European *ǵneh₃- ("to know"), source of, among a whole bunch of others, English know and ken (cognate with German kennen and Swedish känna, both meaning "to know [people]"), Latin nōscō ("I know", Spanish conocer) and Ancient Greek γνῶσις (gnôsis, "inquiry; knowledge; fame").
Gwybod's first element, on the other hand, descends from Proto-Indo-European *weyd- ("to see; to know"), which has another host of descendants, like English wise and wit (cognate with German wissen and Swedish veta, both meaning "to know [things]") and Latin videō ("I see; I observe; I understand", Romance ver/voir/vedere).
As far as I know, nabod is for knowing (or being acquainted with) people, gwybod is for knowing facts.
You may recognise the distinction from other languages, such as German kennen/wissen, French connaître/savoir, Spanish conocer/saber, or Italian cognoscere/sapere. (Or perhaps Cornish aswon/godhvos, Slovak poznať/vedieť, or Hungarian ismer/tud!)