Pkt is a written short form of packet — a small pack of something, often food: a pkt of crisps, a pkt of seeds, 2 pkt sugar in an old recipe. You find it on packing lists, shop labels, catalogues, and notes where the writer wants to save space. It is not a word you say; if you are talking, you say packet. Packet itself is a modest, everyday noun: bigger than a single wrap, smaller than a huge box, though actually people stretch it (a packet of letters, a data packet on a computer). This abbreviation only covers the ordinary “small pack” sense, the one you could hold in one hand.