The name of the dance is prounced Se (short "e" sound like elf)/ lan (an "a" sound like in saw)/ ya (like the "y" sound in yellow). The emphasis is on the middle syllable.  

I do sixteenth century reinactment of a Shetland woman named Sla'ine. She lives on the island of North Uist. She composed the dance which shows her spinning and weaving, for her clan. The dance shows the carding of the wool, threading the spindle or bobbin, spinning and winding the thread from the bobbin. Long ago, a woman followed her man, whether it be to a new home, to war, or to a new country. So Sla'ine follows her partner for half the dance. (RG)