Where does “līna” come from?

līna (Old Dutch) comes from Proto-Germanic līnǭ, from Proto-Germanic līną, from Proto-Indo-European līno- — flax.

Ancestry of “līna”, step by step

Step	Language	Word	Meaning
1	Proto-Germanic	līnǭ	that which is made of flax; line, chord, rope,...
2	Proto-Germanic	līną	flax
3	Proto-Indo-European	līno-	flax

līna — Etymology, Origin & Word History | Etymology Explorer