means Small, easily lit sticks and twigs used to start a fire before adding larger logs.

from From the Old Norse verb 'kynda,' meaning to set fire to or ignite, which gave Middle English 'kindlen' (to catch fire or set alight). 'Kindling' is simply the act of kindling made into a thing — the very stuff that does the catching. The identical-looking word for animals giving birth to a litter is a separate cousin, from Old English 'cynd' (kind, nature), so a rabbit 'kindling' her young and a fire's kindling only sound related.